Stan,
FWIW here is what I guessed for your rig in the DeuceCoupe Gonkulator.
Assuming 3560 lb with driver (that's a guess) and the 390 Holley on top, here is what the Gonk said just by changing stall speed. I am also guessing at the stock stall I have no experience with the 700r4. I usually brake torq all my stuff to check the stall first. My powerglides stall from 1500-1800 or so depending on what engine is in front of them.
1600 stall
2.33 60ft
15.48 at 85.8 1/4 mile
6.99 0-60mph
2000 stall
2.18
15.28 at 85.9
6.77
If it wasn't a lockup this is where I'd stop. May not seem like much gain but 2.33 vs 2.18 in the 60ft is a BIG difference, you will feel it like a greyhound bus hit the rear bumper. And that's 2 carlengths quicker overall.
2400 stall
2.12
15.19 at 85.9
6.66
A lot of the new lockup cars stall in this range. Tops Ive seen is maybe 2600. Given that you have lockup I'd probably stop here at 2400 unless you plan a bigger cam.
2800 stall
2.09
15.13 at 86.0
6.58
I guess this would be ok with a lockup but getting a little slushy around town.
3200 stall
2.06
15.06 at 86.0
6.48
This is great if you need every last fenderlength.
As a last step I swapped on a 600 Holley for another 1 ftlb and +8 hp:
2.06
15.04 at 86.2
6.46
Worth it if you have a free one on the shelf but not to buy one. And the little 390 Holley will be a lot better driveability and easier on gas.
Finally Jay made some good comments - the Gonkulator doesn't separate a "good" converter from a "crappy" one and I've seen both in real timeslips. Cant quantify that so I'm always watching for folks that get incredibly good 60ft times (better than the Gonkulator predicts) and then who built their converter.
If it were ME, I'd use the stock 700r4 converter, get some timeslips, then if you're not happy, get a 2400 or so and see how much things really change.
