I'm contemplating a 4 speed behind the 471 I'm building, it's a 23 spline though, I have most of the big parts, just need a flywheel, clutch & some other small stuff Otherwise it's a 4200 stall & I want to street drive the car as much as possible. I don't know really cost if it would be cheaper to build a 727 or get a 23 spline able to live behind 550-600