What To Do With a Tweaked Flex Plate?

All the old Mopars in the wrecking yards around here were sent for scrap many years ago when the price was high for scrap steel. An auto transmission shop might have something laying around.

My '65 Formula S has a 1979 dated/built in 1980 318 block and original 904 transmission. Not sure what year the crankshaft/pressure plate are. If anyone has the diameter of the two different flex plate "holes", that could be helpful to someone. Or even one measurement would determine which version one had (process of elimination).