With the parts you've selected, you won't have a problem with over powering anything.
Powerglides should be saved for a light car under racing conditions.
Get a TH350, have it done right to handle some torque and continue on.
Gear selector (PRNDL) will have to be changed if that little detail concerns you (I'd suggest it though).
I'd stay between 3:31 and 3:55 on the gear ratio selection.