I dont want to scare you but,I ran basiclly the same compbination in my car when i first built it, The only difference i ran 28 tall mickeys and 456 gears, lanched it at 3500 rpm and shifted at 6000 rpm. I could not keep the diff together, i broke 4 cone style sure grips, 3 clutch ones,, went to spool and then i broke teeth off the ring gear, and the last time i raced it with the 4 speed, i broke the main caps off the centre section. I HAD NO LUCK WITH A 4 SPEED AND A 8 3/4, went to 727 and with 500 plus runs with out any braekage, Then i biult a 416 making almost 600 horses and a transbrake and a 5500 stall and 250 plus runs with out any parts breaking, 4 speeds are very fun but hard on parts. hope you have better luck than i had.