I sort of copied the magazine 400hp 318 where they usex the stock magnum heads.
I started with a 1986 roller 318 went .030 and KB167 pistons. Used a smaller cam than in the mag. I used a 222/228 hyd roller but i didnt use stock mag heads. I used EQ magnums with the 2.02 inlets. I gave them a clean up in the bowls, sort of just blended the seats into the runner and cleaned up the guide bosses. I used a M1 inlet manifold but i probs should have got air gap rpm. Had 9.5 compression.
This motor made 302hp at the tyres on a dyno dynamics.
So i am certain its around the 400hp mark and could get into the 12's
hope it helps some