I run the same with a 904 with out a low gear set . When I went from my stock stroke 367 to my 408 I had to take gear out of the car ( 4.88 to 4.10 then 4.30.s) because I had to much rpm at the stripe due to the 52 more pounds of torque . I tried a low first gear set in my 904 years ago with my 367 and saw no difference. It could be because my converter is pretty evenly matched to my combo .