Originally Posted by Sloan66
Thanks, that helps.
Also, remember that the timing marks will indicate TDC at TWO different times: once when #1 is at TDC on the compression stroke, the other time when #1 is at TDC on the exhaust stroke. You want to line up your distributor when it's at TDC on the compression stroke, otherwise you'll have it exactly 180 degrees "out". Two ways to tell: put your thumb over the empty spark plug hole and feel/listen for pressure as you turn the engine over, or pull the valve cover on that side and watch to make sure both valves are closed with the timing marks at TDC.
Also, you didn't ask this but just in case --- factory orientation of the distributor has the vacuum advance connection on the distributor pointed more or less directly at the driver's side fender, distributor cap wired so that #1 cylinder connector is at about "half way" between the firewall and the drivers side fender. ("Pointed at" the general vicinity of the brake pedal). Remember Pontiac distributors turn counter-clockwise. If you didn't "care" about factory orientation, you could just install the distributor any old way, make sure the motor's at TDC #1 compression, see which terminal the rotor's pointing at, connect #1 plug wire there then work your way around the distributor counter-clockwise connecting the rest of the plug wires in firing order sequence. It'd work just fine --- assuming all the plug wires "reached".