Hey Cylinder heads guys- advice needed

RustyRatRod said
I searched that casting number online and if I am reading it right, they could have come on either open or closed chamber. So it's still possible they could have been machined open. ......IF I am reading that information correctly.

Yep, same casting number but machined 4 different ways with 4 different part numbers. Open chamber, closed chamber, long valve, standard valve.