Cant really compare what gears people are using, The 6R80 has a 4.17 1st so you dont need a 4.10 like a 4R70. Plus 2nd gear is pretty much split in half on a 6R80 compared to a 4R70, you have 4 gears before you get near 1:1. That helps more with a stock converter to keep the RPM up..
Problem with the 6R80 is you cant shift it yourself, very expensive to fix and limited on converter choices. If good ETs are your goal a torque converter can make or break the whole thing, its the converters job to keep the RPM where it should be.
Myself I would do the 4R70, add a brake if you are going to be really racing and not just T&T and you are done. Dont get me wrong, I like the 6R80, but thats because its thereNothing lasts forever, I always rebuild my own autos and just looking at parts costs these 6R80s wont be cheap to fix/rebuild..
A friend of mine and a member here, RDSNK46, has done a coyote swap with a 6R80 and he had it put together with push button shifting on the steering wheel. It worked out awesome. Uses a 2013 PCM that has the select-shift feature on the shift handle, but it was relocated to buttons on the wheel. Left side of the wheel is down, Right side is up.
