There are a few ways to go.
A built 700R4 will cost you a small fortune, but allows you to have an overdrive gear.
A TH400 can easily handle the power for <$1000 but if you have a big gear in the car, you'll lose highway drivability. I have a TH400, high stall TC and 4.11 rear and I won't take it over 60 mph for more than a couple of miles.
My solution now is going to be putting in a Currie 9" rear with 3.70 gear and running tall tires on the street. That should ease my car's screaming on the highway. If not, I'll look into a Gear Vendor's overdrive unit. They're sweet, but cost ~$2k.