The outer edge of the flywheel flange on a 235 crankshaft is where the oil seal rides. So if a bolt or dowel pin is missing, oil will leak from behind rear main brng, fill the oil return area in the rear main cap, and leak out the flange. If the dowel pins can't be left in, its best to remove them and drill and tap for bolts thru new flywheel, or cut them flush with crank flange. I think the 235 is internally balanced, so make sure any flywheel used won't unbalance the rotating assy.
I have heard several reports of the aluminum bellhousing adapter cracking or the flywheel breaking. The 235 starter mounts in the stock cast-iron bellhousing with 2 bolts. This bellhousing is different than any later 63-newer chevy bellhousing, standard or automatic. I believe the PG bellhousing on your car will be different from a V8 PG bellhousing, but you'd have to compare them. The typical PG bellhousing is the same bolt pattern as a chevy TH-350, and since I know the TH-350 won't bolt up, the typical PG prolly won't work either. Some guys are using standard tranny 235 bellhousings and modding them to work with the T-5 5 speed out of a S-10 truck or similar.
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