Toploader - to - C4

Hankerin' to make the swap. Kinda green here. Lookin' for any input on what needs to be replaced, added, or removed. Also any suggestions from experience is appreciated. Pros and Cons. What type of trans cooler should be added? How big of stall? Would I be better off with an AOD? Are there any issues with the install of an AOD? Want trans to handle near 600HP (future mods). I'm runnin' a 390FE in a 1966 Fairlane Club Coupe. 3:91 Traction Lok. Hooker Super Comps. Additonally, are there any mods needed to the trans to hold the torque. I have a friend who will build to spec. Thanks to all in advance for any input.

My opinion - if your going with 600 HP, use a C6. The C4"s are a good trans, but not sure it will handle 600 HP. Don't know much about the AOD's