Port matching a BBC Rect Port Perf RPM

I was noticing the port dimensions on the Perf RPM rectangular port intake are a good bit smaller than the 1.75" X 2.5" ports on my Dart heads. Maybe by about .25" in each direction. This also seems to be the case with some of the other head ports I compared. Is this intake just designed for a smaller head or ? Is there enough meat in the runners to port match this thing that much?

I'm asking because I'm likely gonna be stuck with my Dart 320 heads for now but the 4500 intake is gonna have to go. I'm looking at the Perf RPM with maybe some port matching and a cut down plenum divider.

Thanks,
John