I remember when I picked up my stock lower that he ported I talked to him about the uppers. He said that you can port them without cutting the intake in half by removing the plugs and taking a long bit and working the runners. The length can be made more even and smoothed out. He also said that the work was realy not worth it for the time involved or something.
the upper flows like 190cfm and the lower that he ports makes that basicly the flow range...if you need more you prob. should be looking at a diff. intake anyway.
The 94-95 upper is harder to improve than the 87-93 upper. Bascially, opening it for a 65mm TB and matching up the lower and upper to the gasket are about all that's worth doing. Even at that, I've seen a ported stock 94-95 intake make 255RWHP/311RWTQ - Rio5.0's car with Thumper heads and a Steeda #19 cam.
my car made similar numbers with it being lean.......so i would say the uppper TB matching, and upper to lower matching is sufficient enough for the stocker