[SFfiredog]

P,

I wanted to know some specs on your engine so I could answer your question properly.
The flow numbers on your heads are good.
Most uniformed people only look at the max flow numbers but the reason your motor makes so much power is because the 70%-lift flow numbers are very good and only slightly less than the max lift numbers.
Your heads may not flow huge numbers but they flow with very high velocity which is more important.
The valve is at 70%-lift twice in a power stroke (on the way up and on the way down) but only once at max lift.
The duration @.050 and the lobe center of 112 deg is why the engine makes good power with reletlivly low compression.
The ramps of the solid roller help make more power as well. (keep an eye on the valvesprings and distributor gear)
I have no problem believing the horsepower numbers.
With a bit more compression and the lobe centers a bit closer it would make power in the high 5s and pull over 6000 rpm.
--my 02
--Mike