My 286 heads flow 290@.700" on the intakes and have a very mild port. I don't have any exhaust flow numbers because my friends homemade "bench" just sucked, didn't blow.

I would contact Marlin Bogner. He had some Batten MW heads for sale a couple of years ago. Pretty wild looking stuff, but I don't think he ever told me what they flowed. His good SS engine was making about 700 HP with a modified crossram, no sheet metal intake. Or try Jeff at MCH, maybe he's done a MW head?