Trick Flow small block heads
IMM Engines facebook page says the heads flow 290cfm @ .500 lift I would think that cam should make more than 439hp with those heads
What is the compression ratio?
The thing here is, at least IMO, that even at the lift the cam has, there’s no real cylinder feeding time. The head is seeing only like 80% of the lift on the curve that sees the lower lift twice and barley gets into the peak lift score it rapidly flys past.
If the lift was increased, generously!, the power would respond. I also believe that more duration would be a huge plus. Adding in cylinder filling “time” would be great.
Also, as mentioned, an RPM up top a head like this (or likewise a fully ported set of RPM heads) is hampering the ultimate power output of the engine. While great for torque production, HP suffers because the intake, as cast, OOTB, is a serious limitation on best performance HP wise. Even if the intake is well ported it cuts the top end off.