Hi Steve,
By the serial number it looks more likely to be a C3 on a Santa Barba action. As for the weaver bases some owners fitted these when they changed to a scope with a bigger tube diameter, (ie 30mm) they should be numbered 45 & 44 or 46 / 47, if thats the case they are definately C3's.
Some M82's from Canadawhich would be known as C3's which were then knocked out as the 1200 TX, a good clue is that the rear scope mount holes which would be large 2BA in size, and the mount would have to be modified to take that 2BA.