Closing shims Ducati 500 Desmo Parallel Twin

Hi there, I’m restoring a 1980 500 Desmo Parallel Twin, and am working on the valve gear, I have found getting the opening shims no problem as they seem to share parts with the Bevel motors. Closing shims do seem to be a problem. Any one out there know of a source, or any good business who can accurately grind the ones I have, they are all too tight, and will only tighten further with use.