360 questions

915s...some variations did exist. My brother has a set that's minus the "1" in the number..348915...I think they're a service replacement casting, but I'm not sure.

In any case, 915s are J heads...have them checked for cracks, a good 3 angle valve job, bowl blend, back cut valves, and a port match will yield some good results. If you want more, start reading on how to port heads or you can have someone set them up for you. Just depends on what all you expect out of it.

Do you have a hp or ET goal, or just a stout running street car?