I just got a call from the cylinder head shop. They said that the installed spring height on the intake side is 1.550; it should be 1.750 for my springs, and, unless I'm mistaken, the stock installed height should be 1.780. Thinking that the problem could be the overall length of the replacement valves (5.078), they tried an off-the-shelf valve with overall length of 5.090 (same as stock) with the same result. The intake seats, as far as I know, are original, are within specs, and reusable. Other than taking the original valves that were removed from the heads to the shop and having them recheck the installed height, I don't know what to do. Is there a plausible explanation for the installed being short by .200?