Well, My current build is from a late 60's truck which I doubt has hardened seats. So I will need to replace these instead of machining/grinding them to the 1.90 or 1.94 dia? What about having my SS 1.94 turned down to 1.90? Is this the best of valve size vs chamber size? Looks like it might be so. I'm kinda cautious about having a machine shop hose up my head while doing the valve seats. Anyone from the DFW area know of a good machine shop that has and will do this right? One more question......do I have someone turn on a lathe or grind my SS valves????????