First thing I would do is lighten the car up some. Matts 1970 Duster weights slightly over 3000 pounds with cage, frames tied, factory bumpers and brackets, 2 front seats, rear seat, factory glass all around, factory wind up windows, factory carpet, 727, and all metal factory body parts except for his 6 pac hood. Next I would go with a powerglide as they are "super cheap" to build and maintain and parts are always available.