I would add a set of Headman Headers to the combo.
Truck headers are nothing like A body headers, no dents required. You do not even have to un-bolt the engine, just drop the starter and oil filter.
The drivers side slides up thru the bottom, and the passenger side will drop in from the top. If you are careful you will not even scratch the paint on the headers.
And I would leave the 4.56 gears.