Best guess on 416 motor

What do your heads flow?

258 @ .600"
This was with a 2.02 intake, a quickie bowl blend and our valve job, with no clay on the intake port entrance.

Remember too, many flow benches vary. It's not a flowbench "race", it's just data in my book to gauge improvements. Brian @ IMM sees 270 from his RHS @ .600 IIRC.