I ran that test on my 700 HP dyno mule. What I found was that by port matching the Performer RPM to the intake adapter, you picked up a little top end HP, and lost a little midrange torque. I would recommend against port matching, even though there is room in the casting. The port mismatch doesn't seem to have much of an effect on power even on that 700 HP engine, so despite the fact that there is room to do it in the casting, I'd probably leave it along.
The thread below gives all the details. See page 6 of the thread for the unported vs port matched test, and page 11 of the thread for bar graphs showing average torque, average HP, peak torque, and peak HP for all the manifolds tested on the adapter, on this engine.
http://fepower.net/simplemachinesforum/index.php?topic=4760.0