440 problems

440superduster said
added more timing and fuel seems like problem got a little better . also swaped out ballast resitor small problem now and again but will know when I drive it this weekend.

Nice work. I think you would know it if you wiped a cam lobe, there would likely be much worse symptoms than backfiring through the exhaust.

Obviously, swapping the cam changes the entire dynamic of the engine, it stands to reason you would need to fine-tune the timing and mixture.