before i got the dart i had a 76 aspen r/t with a 340, 904 w/low first gear, 4.30s gears w/ a 28in tall mickey and was runnin 12 teens at 110 while driving it on the street. i think you'll be ok w/ 4.30s, you'll see improvment. it was a 9 1/2 3800 stall 60'in low 1.60s