Best options for buying/building an aod for drag racing (street/strip) use?

[white_stang]

My 93 mustang has an 89 stock aod in it. The car is being built for street and strip use, and I want to keep an aod in it. Once built, the engine (302) should hopefully be 400+ horse with nitrous, so I need one that can handle that. What are my best options for buying one or building one, preferably under 2 grand, or 2500 to buy a new one? Ive looked at silverfox, lentech, patc, etc, and im justnot sure what the best kit and valve body would be or if its better to buy an assembled trans.