Guaranteed, you will absolutely need extra nose weight on a Byron Hellcat regardless of the engine you use .... unless of course it is a small block Chevy V-8 or something like that.

Great flying airplane and in my opinion the best of the old Byron warbirds. Also quite fast for those who care about that. I built and flew one with an older 3W-60K on it ... those engines were a bit on the heavy side and I still added weight. Can't remember but I think my all up weight was 28 Lbs. or something like that.