Might want to contact this guy to see if he's still doing the porting. I had an older link for it,,, but it doesn't look like it's showing porting services on his updated home site. If he is,,, you could get the whole system ported (plenum egr wall removed and "gasket matched", runners "gasket matched" and ridges removed, smoothed T/B, and mildly worked base) for less than corvetteplenums wants for just the plenum port.
SPD Porting Skulte Performance Designs - Skulte Performance Designs (updated home page)