You don't mention any specs other than 9.5-10 cr. A short cam (very low duration @ .050, tight lsa, early intake centerline, fast ramp, or a combo of..) with that cr can cause very high cylinder pressures/detonation. Have you checked cranking compresssion vs "build" spec? Might very well be simply a timing curve issue but there's a reason you'll be having to recurve it from the former build. And that would be higher low rpm cylinder pressure than it had before.