I did the same more or less to my barn find 65 Chevelle SS and kept the front drums - it's a 250hp car and the drums are fine for stopping so far IMHO and mine are manual...

Great looking project, good luck!
Anthony

I drove a 64' Chevy II wagon (355 and a 4 gear) for years with drums on all four corners. NEVER had a problem with that sent up even towing a boat and trailer ... TAZ