323 355 or 373 gears??

Johnny Mac said
IF i did a GM trans, it would be 4l70E based, which is more like a 700R4 size. Now the 4L80E is HUGE. 1. its overkill for 500HP. 2. Yes, i think OP is going to have to do some major cutting.

Yeah read an article about 4l80e, looks to big. Give me a call when you can, left my number on you VM.