I have my 416 stroker bottom assembly 9.5 to 1 dish pistons at 65cc and I already have a set of J heads small valves 72cc brings my combo to 9.1 to 1 compression. These Js are they to small? , I have a set of magnums also id#5300 6671 was wondering if the magnums would be a better route for my car? 72 Cuda w/727 3000 stall Street car and I have an ld340 already w/a demonsizzler thermoquad.What should i do.Are there any problems running these magnums on my 71 340 block? Thanks Any help appreciated