Lots of good advice here... IMO more gear ( 4.10, 4.30 or 4.56 ) less converter ( 8 inch ) just a quick note : years ago my good 340 was broken and I had a basically stock 318 ( 340 cam, LD4B intake, 750 carb, and stock 360 heads ) with a 904 , 10 inch converter and 3.91 gears it went 13.20s in my 3200 lb Dart I put in an 8 inch Turbo- Action converter and it went 12.60s with no other changes. I went 11.30s with a 340 at 9 1/2 to 1 compression , ported " J" heads and a 557 lift Mopar Purple shaft cam . I went 10.50s ( 10.40 best ) with a 360 Magnum short block, 11.5 to 1 compression , W2 heads , 590 lift cam, made 549 hp ... currently set up has gone a best of 11.07 at 119 with the same 360 Magnum short block ,40 over to 367 c.i. , W2 heads , 585/595 lift cam, 10 to 1 compression on pump gas made 527 hp and 467 tq on the dyno. All my combos are ran thru the mufflers ( 3 inch Flowmasters ) with either 1 7/8 TTI headers or my previous Tubular Automotive 1 7/8 headers , Victor intakes and an AED prepped 750 hp carb. I wont even get into my R3 block/ Indy 360-1 head 408 thats a whole story in itself... these are just a few of the small block combos I have ran over the years.. your results may vary