what I found is it's easy to get the clutch pressure plate. Any 12" pressure plate made for a SBC will work.
This is the kit I used for mine.
https://shop.advanceautoparts.com/p/...62-1/5332559-P
the hard part is getting the correct disc. all the SBCs and L6s spin the opposite direction of a V6 305, so you'll need to use a different disc. I just reused the 11" one I had and it's all working fine.