I vote for the 700r4. I have one from Bowtie Overdrives and I love it. The install was easy. They sell a TV kit that lets you adjust shift points and how hard the shifts are. Mine has a 1 year, unlimited mile warranty. Price really isn't that bad either. Check out
www.700r4.com. I have the Stage 3, 2200 torque converter and TV system. The Stage 3 is good for 600 horsepower they say. My only advice is to get a really big RV heat exchanger.
Also if your motor bogs get some more HP.