E85 converted 4160

So I bought a converted 750dp last year. I finally got it installed tuned it and the way my setup is currently it doesn't like it much. Starting in 1st it'll blow the tires off into 2nd. Cruising in 2nd or 3rd then going WOT it goes mad lean on my Lambda gauge. After it gets past the lean stumble it pulls hard. I'm currently running a 408 with 904. Due to the economy I had to run the converter I had which is a Hughes 2500 stall but almost acts like a stock converter. So question is would I be able to convert my 4160 without buying the $400 kit I've been seeing or is that the only way?