Howdy! Don't fret too much about removing the carb and manifold, that's one of the easier jobs to do on a Pontiac. A few tips: If you haven't separated the coolant crossover from the rest of the intake, then make sure you drain enough coolant from the system to keep it from pouring out of the fronts of the heads when you pull the intake. Test fit everything. Make sure the curved shapes on the cover match up with the curves on the front and rear of the block, especially at the corners. Massage the arcs if you need to. I like to "attach" the pan seal to the pan itself with silicone sealant and let it sit for at least an hour to partially cure up before I install it. I leave the other surface dry. On that valley cover seal surface on the block and heads, put a small dab of silicone in each of the 4 "corners" where the block and heads meet. Don't go crazy - you're just trying to create a seal at these points. You don't want globs of sealant coming loose and floating around in your engine, potentially clogging your oil filter pick-up. Watch the long edges of the valley seal and don't over-tighten. It'll have a tendency to push out below the intake ports if you do. Don't forget about that small bolt that pulls the intake forward into the back of the timing cover. Make sure you get the all the sealing surfaces nice and clean on the rear of the timing cover and on the intake, then reinstall the rubber seal with a *LIGHT THIN* coat of good silicone sealant on both sides. Install the intake and tighten that small bolt just enough to make the surfaces touch, then let it sit for an hour before tightening that bolt. When you're going back together, install the intake with all the bolts started and maybe barely finger tight, but not tightened, then tighten that small bolt first before torquing down the rest of the intake bolts. Use quality gaskets. I like the Felpro's that have the sealing rings around the ports. I install my intake gaskets dry on both sides because I like to be able to remove the intake manifold several times without having to replace the gaskets. I've also separated the front coolant crossover from the intake which provides me with two benefits: I can pull the intake without having to open up the cooling system, and tightening that small crossover to timing cover bolt does not mess up the alignment between the intake manifold and the intake ports in the heads.
Don't get in a hurry when working with silicone sealant. Before applying final torque to the bolts, you want to hit the "sweet spot" where it has cured up enough to have adhered itself to the mating surfaces really well, but has not yet gotten so firm that it can't "squish around" some when things are tightened down. Once you've got everything torqued, leave it alone and let it final cure before you start it and heat things up. I like to allow at least 12 hours regardless of what the information on the tube says.
Getting these engines sealed is more about how much care you take in fitting and assembly than it is about the specific seals/gaskets you use.