[DanEC]

I would have to check later when I'm at home but I think those may be the same heads I'm running - 390 hi po or police interceptor heads used on the mechanical cam 390s. What you have will depend greatly on what, if anything, has been done with them. Keith Craft ported, polished and installed 427 valves in the ones I have and from what I can tell they are probably roughly equivalent to 427 LR or 428 CJ heads. What intake is on there - a medium riser or a low riser?

But, Chas guess is probably as good as any and would seem to line up with mine pretty well. Mine is built pretty mild with 9:1 compression and a 4.25 crank for 459 cu inches. I'm using the 427 LR intake which from the Great FE Intake Manifold Shootout book is a big torque maker. It made 470 HP and somewhere around 535 ft lbs of torque (torque had already peaked when he started his pull). It seems like a well assembled, stock 428 CJ will often make around 420 HP so I would guess you are around that or maybe a bit higher.