I want to use my T56 with my 400 block. Can I just use a normal 2 pc seal flywheel and drill the bolt pattern in it to match the LT1 pressure plate? And then get it balanced for the 400?

 

The LT1 flywheel is much thicker than a regular SBC flywheel. Unless you shim it out substantially, you'll have issues with the clutch slipping. I don't know exactly what the difference is...it may even be too much to shim.

Centerforce makes an external-balance 2-piece-seal T-56 flywheel (part #700173) but it's pricey at around $400.

 

no, the clutch works backward. the throw out bearing sits on the eng. side of the pressure plate and when it gets pulled toward the trans it allows the clutch to slip. (the complete opposite) and because the bearing and fingers aim toward the eng. the flywheel has a very large area molded in the cented to make room If you look at a picture of one you will see.