quick 318?

Ive been reading up on the mopar muscle parts book 318 build,the one with stock magnum heads.400 hp 509'100 shot.lets say this engine is in my garage identical.if I run my 275/60 tires and change to 410 gears what would I have to change?mean318 build is almost identicall it ran high 12s almost mid 12s but runs high 11s with 100 or 125 shot. Everything seems easy.and should run awsome,and it should be cheap