What are you going to use for pistons and rods?

Since you're going to the extreme of using the 6.4 crank, I'd go with the eagle heads. I dont know about what thickness of head gasket youd have to use though. You can use 6.1 intake springs with shims on the eagle heads per Stu at Intertia Motorsports.

What intake and engine management system are you gonna run?

Sounds like a cool build.