Originally Posted by cobalt327
This is a 1-piece rear main seal block. Factory 327 cranks are 2-piece rear main seal blocks. You'll need a 1-piece to 2-piece RMS conversion setup to use a 327 crank.
Why not use a 350 1-piece RMS crank...
This is if you want to keep the 307 together, obviously. The problem w/using a 307 crank for a 327 is the balance will be off, and there's a chance the crank will need Mallory added. That gets expensive real quick. Of course, you could build it and not balance it, but I wouldn't recommend it. You can get away w/using a stock 350 crank and the balance will not be perfect, but will be closer than a 307 crank.