Here is what I learned on my recent cam replacement. I've disassembled and reassembled a few poncho motors in the past but finally figured this out on this last job:

The crank keyway is at about 1:00 when the crank sprocket mark is at 12:00. At this position the number 1 cylinder is at TDC. This can either be TDC starting the power stroke or TDC starting the intake stroke depending on the cam position. It turns out that when the mark on the cam sprocket is at 12:00 that makes it TDC starting the power stroke.

The timing chain can be assembled with the cam sprocket mark either at 6:00 or 12:00 (with the crank sprocket mark always at 12:00). I prefer to do it with the cam sprocket at 6:00 which makes it easier to see the alignment. Once the timing chain is installed I turn the crank one rev which puts both timing marks at 12:00 which puts the motor at TDC of the number 1 cylinder ready to fire. You then leave the crank at this position and reassemble the rest of the motor.

You can install the distributor in the number 1 firing position and don't have to be worried about it being 180 deg off. It also turns out that the fuel pump goes in easily because it's at a low position of the eccentric. This all was likely purposely designed by the Pontiac engine designers to ease engine assembly at the plant.

Thought I'd pass this along. Some of you probably already know this. I wish I'd have known this years ago. It would have made my life much simpler.