I have put in 1.88 intake valves into the 302 heads. Using very good multi angle Serdi style cutter and minimal port match to stock 318 steel intake gaskets intake went 240 at .500 lift. The ex. port on those heads aren't good. they have the hollow floor/minimal short turn I put 1.60 ex. in them also. I want to say they maybe went 150 on the ex. I have the flow numbers in the shop.

The 308's have the much better ex. port, completely different, along with the larger better intake port. Sometimes larger machine shops can get /have certain re-manufactured casting number heads. You can request them. That's how I got a set for a 360 I built for my truck years ago.