Just to add to the Pontiac comment.....
All Pontiac V8 heads had fully machined combustion chambers. The flat chamber floor worked well with the 30* seat, & they used a valve with a flat head because the tulip shape does NOT work with the 30* seat. For the Ram Air 4 engine, they used the 45* seat, 1.65 rockers [ instead of 1.5 ] which added about 0.045" more valve lift.....& made about 4 hp more.
