Part of building power with exhaust manifolds is trying to keep the intake port velocity up without the benefit of exhaust scavanging.
The bigger the intake port, and valve, along with more low lift flow(which almost always means more flow in both directions), relative to the size of the motor, the harder it is to build velocity at moderate engine speeds.
To me that means that you'll want to make the motor as big as is practical to use the TF head with it's fantastic low lift flow and 2.19 valve in this type of application.
That is a good thing to go ahead and point out. When I switched from my 470 shortblock to a 512 shortblock I also changed from RPM heads to CNC ported Mopar 452 heads. I think that a 512 would be big enough to work with the TF 240cc heads but you might want to be even bigger than that to keep the velocity up.
You can spend a ton of money figuring it all out that is for sure!
