Your thoughts on transmissions

[Beatcoaster]

Now that I am finally done restoring the interior of my truck it is time to work on the drivetrain, beginning with my TH350 that is leaking all over the driveway. Supposedly the previous owner had it rebuilt, and it did shift fine when driven, but I plan to put some power through this thing and question whether it will be able to handle it (350/355/383 @ 350-400hp) with it's unknown to me history and 1969 metals. Would it be wise for me to take the $300 for a performance rebuild kit/parts and time spent, and just invest it in a new summit tranny already done for $650 that can handle 400hp? Then, I question that because I know I am going to need/want an overdrive gear as this truck will be making 300mile road trips over to our property for many summers to come - which leads me to finding a 200r4. The whole TV cable worries me a bit though, as there are some horror stories on the net with people not having it adjusted correctly, and frying their new tranny....You all have any thoughts or ideas for me?