For a Tremec you might consider X2C Motorsports' version. They rebuild the new trannies and blueprint them...they hold a lot of power! And the price is right too.
www.x2cmotorsports.com
As for the engine, that is a lot of cylinder head for only a 302/306. Too much IMO for a sub-6000 engine, but it can be worked with. Look into a Comp Cam hydraulic roller (assuming this is a roller blocK). They have the better of the off-the-shelf designs and those heads will make use of the extra lift.