The better way to adapt the 400 is with the coan plate that let's you use a Reid bell. Then later if you get a Reid case it'll work on it. Plus they're way straighter than jw.

Here's the trans with the coan/Reid



The car has a 727 in it now but you can see where the rib was and is now gone. That's about it for body mods. Get the longest tail they have for the 400. The D shaft will be super long. I had to go carbon for the length power, and rpm