360 swap 1965 Barracuda

What do i need to do to replace my slant six with a crate 360 (400plus)hp, will a a833 tranny hold up? i would like a keisler 5spd, but thats a little more money than i want to spend and do i need to replace my 81/4 with a 83/4

I was originally going to build up a 318 Hopefully 300plus hp with a A833 and keep the 81/4 rear, i think it would get much better mileage. Any thoughts?