If I did the test(which isn’t likely), the stealths and rpms would only get mildly ported.
The cnc stealths cost the same as the TF 240’s, so for that price which head to buy is a no brainer(to me).
To buy some rpms and have them cnc’d, it’s even more expensive than the TF heads..... so again, a no brainer.

Power wise, I think a prepped EZ would be in the hunt, but they would be even more expensive.

For me the question I’d be looking to have answered is...... for “x” amount of additional dollars spent over the cost of ootb Stealths or RPM’s, or even when updating the heads with some mild porting, vs the ootb TF240’s..... how much extra power do you get for your $$?

I’d have it where all the heads had the same chamber volume to eliminate that variable, and build the long block with the intention of making 600-625hp with the mildly reworked RPM heads, then see how the other heads compare at that power level.