Even with the wider static (sitting) valve clearances the old-school race cams are a tight fit once they open. Certainly the closer lobe centers, 103 degrees for Montjuich and NCR, compared to 110+ degrees for the 900 cams, contribute to this. Even though the lift on the 900 cams is higher they open and close quicker. And their lobe separation is greater than the race cams. Thus, they are more tolerant of close valves.

dearest mike, you have done an excellent analysis on all the possibilities and performances, the #p# cams on the point of maximum opening of the intake valve the goniometer reads 103, 104 degrees, as a racing cam axis should be, I have not never tried and tested other types of camshafts, I have always used P camshafts because I have always had them available and in Italy they were replicated quite well by hold racing spare parts, by Mario Sassi before it passed away.