Intersestingly, Nicks Garage on youtube just tested a 390" 318 with ported factory Iron heads, 10.2:1 with a Performer RPM and a really mild 231/237 @.050 hydraulic flat tappet with factory 340 Manifolds and it made 405 hp at 5400 and 440+ LB/Ft through the middel and I would think his dyno is very conservative (or at least real).

I would think headers alone would put it at least at 460 lb/ft and +430 hp at about 5600. It any event it's a sweet hard pulling street combination, probably enough to put an A body with decent traction in the 11's and a mid 70's D-100 in the 12's.

it's funny, I commented on one of his more recent videos that most people (that actually watch dyno videos on youtube) would really like to know more specifics about the head and cam specs...and (Thank you Nick!) it looks like he took that advice to heart,