My old pump gas Duster went 10.60s at 124.+MPH the first time out weighing 3450 Lbs. with me in it through the 3.0 exhaust and air cleaner on. I had a custom 10 inch Continental converter made for it off the engine dyno sheets(612 HP at 5500 RPM with 644 Ft. Lbs. at 4500 RPM), that converter would only foot stall 2300 RPM in first gear before pushing the front tires through the beams. I later broke it at the track and replace with a Turbo Action 8 inch SS/AH converter that drove much easier on the street and at the track and made my car go .2 ET quicker and 2.+ MPH in the 1/8 mile
My message is get the best converter you can get, Call Paul Forte at Turbo Action and have him make a converter for your car now if you can
I have one customer that I got a FTI drag race only converter and Powerglide for his S/P bracket car and it works okay but they got sold after I bought that one and I don't know how good they are now