Received the Trans Dapt from Jeg's today. Way to go Jeg's!
Motor bracket is very nicely done with 5/16" and the clamshells look pretty decent. Loaned my camera to my daughter so I will have to get my wife's camera so that you can see how close the fit is!
It looks like a 7" piece of 3/8" x 5 will be almost perfect as to height! Weld in the front part and drill/bolt the motor mounts in place. Figured that if I want to do any future work it would be easier than to weld everything in place. Time and vibration will tell!
I was concerned about having too much of a lever effect from the engine weight on top of the 3/8" plate but this arrangement is pretty close to the crossmember and actually thicker than the crossmember!
I've located some F-body manifolds locally so I'll go check out how they work with this setup. Vette manifolds are a little harder to come my in my part of the world