Here is your engine post that got an answer, but sometimes you have to be persistent or "bump" your post as these posts get buried by other posts due to the poor listing set-up this website uses. It used to be much better, they they had to go and try and improve it - not.
So here are your choices for your build as you posted them:
Planning Overhaul with:
Thermal clean/mag check block and heads
Valve job to include new stainless valves/seats/guides/seals/springs as appropriate
Bore/Hone .020 (torque plate)
Deck Block/Heads minimum required to flat
Cut/Polish/Balance Crank and rotating Assy
Forged Speed Pro pistons dished for 9.3:1
Forged I-Beam rods
Comp Cams XE262H
Roller Tip rockers 1.5:1
Stock 1968 Quadrajet intake
SMI Stage 1 800 cfm Quadrajet
Ram Air Exhaust Manifolds 2 1/2” exhaust
OK, lets break it down.
1.) Thermal clean/mag check block and heads - YES
2.) Valve job to include new stainless valves/seats/guides/seals/springs as appropriate - Yes, but install 7/16" Big Block Studs to replace the factory "bottleneck studs" which are prone to snap with higher valve spring pressures/lift, BBC studs means poly locks to adjust the rocker arms, Pontiac uses different length valves - use Ferrea Stainless stel valves and decide valve length to ensure you have enough stem length for a higher lift cam if so selected, have the intake passage inlets gasket matched (you can do this yourself), clean up the intake passages of any rough parting lines & "burrs" (you can do this yourself), get a 3-angle valve job, bronze valve guides, Viton valve seals which means cutting down the valve guides for fit. Upgrade to new stamped 1.5 rocker arms for a more accurate rocker arm ratio. These will have an elongated slot at the rocker stud for higher lift cams so they don't bind, They also come with grooved rocker arm balls for better oiling. You DO NOT need roller tip rockers or full roller rockers for the street.
3.) Deck Block/Heads minimum required to flat. Are you talking about "zero decking" the block so the pistons are flush with the bock at TDC? or just checking for squareness/straightness? Zero decking can be OK, but this will have a bearing on compression, so you have to know if "zero deck" or stock which puts the piston about .015"-.020" down in the cylinder. The heads don't need any big cuts, just light touch to ensure a flat surface.
4.) Bore/Hone .020 (torque plate)
Cut/Polish/Balance Crank and rotating Assy
Forged Speed Pro pistons dished for 9.3:1
Forged I-Beam rods
Purchase a Butler stroker kit/assembly - best bang for the buck and includes all these parts in the kit and far cheaper than individual part purchases - 461 cubic inches so you can pull extra HP/TQ and keep the engine very streetable with a mild build. Once you know the bore size the block cleans up to, then order the matching pistons which will be Ross. At the same time, get the tops of the pistons cut to match the closed chamber shape of the "670" heads and the correct amount of dish to give you 9.5 compression. With closed chamber heads, you can go 9.5, but 9.3 is good if you want to go with it. Let Butler know what you have and then they should be able to provide the specs for the piston as needed, or other recommendations.
5.) Roller Tip rockers 1.5:1 - Covered this earlier. Not needed, save money.
6.) Stock 1968 Quadrajet intake & SMI Stage 1 800 cfm Quadrajet - Good Choice
7.) Ram Air Exhaust Manifolds 2 1/2” exhaust - Good Choice
8.) Roller Cam - NO, don't need it for a street car. Save your money. If you do you go roller, you need a lifter galley brace so you do not take the chance of busting any lifter bores with the roller cam/stiff valve spring pressures. Hydraulic flat tappet cam is fine, don't get BS'd into all the fear tactics of using one. The factory 068 cam is always a good choice. There are other cams as well. DO NOT select a Comp Cams cam (or any other) having a 110 LSA spec. These cams will build/raise cylinder pressure and not what you want when lowering compression. If you had a, 8.2 compression, then 110 LSA would wake it up nicely. The wider the LSA the better the vacuum if you have power brakes. The more duration you select, the higher up into the RPM range you have to spin the engine to take advantage of it and you sacrifice some bottom end grunt. Not a good pick for a stock automatic and 3.23 gearing.
9.)Use a good cam break-in lube on the lobes like a paste which won't drip off if the engine sits at all. I have not used this, but I will use soke form of a break-in paste on my hydraulic solid lifter cam/lifters. Here is just one example:
Find Isky Racing Cams RL-1 Isky RevLube and get Free Shipping on Orders Over $99 at Summit Racing! Isky RevLube delivers unequaled protection for camshaft lobes, engine bearings, lifters, distributor drive gears, timing chains and gears, wrist-pins, rocker arms, valve stems and guides, and...
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10.) Milling heads/block will most likely require new pushrods as the length may need to be adjusted to get correct rocker arm geometry.
11.) Keep quench/squish around .040"-.045" which is easy enough if you zero deck the block and use the Felpro head gaskets which compress around .041"-.042".
12.) I like the addition of ARP main studs, but the factory main cap bolts are heavy enough. If going ARP, then you will have to get the mains line honed after installation.
13.) Use the Best brand graphite rope rear seal.
14.) Use the Butler blueprinted Pro 60-PSI oil pump. You do not need or want the 80 PSI pump.
15.) Use a 15W-40 oil, not 20-50W. You may even be able to use 10W-30 depending on bearing clearances, but 15W-40 is my choice for a HP street engine.
16.) New Harmonic Balancer to replace the old dried out rubber inertia ring.
17.) New water pump divider and sleeves and clearance the impellar to the divider.
18.) Distributor? Make sure it has the vacuum advance feature - do not eliminate this.
19.) Save money on the roller cam set-up, roller tip rockers, and invest it back into the Butler stroker kit.
Install a "tight" 2,500 stall converter. It will have little slip during easy throttle and crusing. Nail the gas and it'll come alive. Doesn't put the extra heat into the trans like a "loose" 2,500 converter.
How did I do??????