400 block

915 heads have put plenty of old school builds in the low 10's high 9's . Ya there are a lot of better heads but if you got them use them. The problem is you say they are rebuilt oiled up on the shelf, if your building a stroker your going to want at least 2.14/1.81 hi flo valves in there with a good 4/5 angle valve job & a good bowl blending and deep port match thinning down the pushrod pinch .