I located and acquired an E0BE-6090-BB head, probably from an 83 Granada, to replace my C6 original head. I'm in the process of prepping and painting, decided to compare the intake valves with my original just for verification. Found them to be the same, 1.649 instead of 1.75 as indicated as spec for the head. Is it safe to say that someone replaced the intake seats and valves with what was used in the earlier versions? Should a machine shop be able to acquire the appropriate 1.75 seats and valves?