I believe the results will be very worthwhile. The mistake people made back in the day was they "Hogged out" everything thinking about those big Hemi HP numbers. Removing the rough as cast finish, blending parting lines and rounding off squared valve guide edges can only help. Are you gonna smooth the combustion chamber surface finish? Some say leave it rough to promote mixing and others say smoothing it takes away carbons ability to cling and build up. I polished my J head combustion chambers and exhaust bowl/ports because I had a cool Dremel and was having fun. Left the intake ports as done with a course cartridge roll. But I still have not installed my heads on anything.