4 speed od or 5 speed
Actually, on the LBE 10 pound aluminum flywheel, I do believe the ring gear can be swapped out. It's custom made.
As for the stock flywheel, you are right about the ring gear.
It's either that, or buy a heavy *** flywheel, or change where the pocket for the starter is, ( aluminum fabricating) or, get a machinist to work a miracle and somehow put the bellhousing pattern on to a Lakewood steel bellhousing, I bet you're rolling and laughing right now, but I bet it can be done.
That's why I said I have to figure it out. I'm not too crazy about just using standard heavy *** flywheel.
The old 273 and some of the 318s use a nine and a half inch clutch. Those flywheels weigh 18 pounds or less.
I have two of those cast iron bell housings, I once thought about using one on a figure 8 car that I have.