there are all these aftermarket heads with largish oval-smallish rect ports. does anybody make an intake that falls about halfway between the 2 standard port sizes?

You can buy cnc'd intakes from Brodix

I believe GM has a CNC dual plane oval port intake for the GMPP aluminum oval heads, which are the same as the Edelbrock heads..
Part #12363421 for spreadbore carbs and #12363407 for squarebore.

I believe this to be true, but never bought them.....so do your homework before buying.

What heads you have? The old torker ll intake is what I used with dart 265cc oval ports and was a good fit.

Very similar if not the same 049's size port

My Team-G intake matched my ported 049's very well. But i'll be switching intakes next go around.

a pair of 7215s fell ion my lap. 101 cc chambers. 2.19 undercut intakes 1.88 exhausts. but in the old days apparently people thought it was a good idea to open the top of the port up to rectangle height. these were opened up about half way there. you can see the top of port just above a standard oval intake. apparently weiand team G and stealth have enough meat to seal a rectangle port with the oval intake. and it looks like the whole top of the runner is thick enough to enlarge the runner a ways in. though the more I think about it, I am considering epoxying in the top of the port and running an oval intake.

Dart oval single plane has enough meat to cover a rectangular opening. And, it's a good intake.

Most flow in a port is usually on the top of the port, thus why people raise the roof.

But when you open up an oval, you can only really make the ledge into a rounded ledge. There is no meat a half inch in from the face. You would have a very high flow pcv vent. Best bet i guess would be just run a rectangle intake.

if it's a budget build and or you don't want to hassle with trying to match just put the rectangle port on and and run it. It's not uncommon and I doubt you'll see any power loss. We expermitted with this some years ago and was surprising.