Finally got through moving furniture and hanging ceiling fans and got back to the GMC last night.
...and the winner is... condenser/points. Flipped the posts on the coil so positive to distributor, new condenser and points (old ones looked bad when I pulled them. Pulled and checked plugs and tweaked the gaps so everything was right. Popped right off. Got her running by doing shade-tree timing (turn distributor until she starts, set for best idle, then slightly retard). I'll take her out today and see how she goes down the road, Mighty glad to get her going - I've got to move her to another house and it'll be much easier under power.
Thanks for all the suggestions!