Tim,
With just the 2 crankcase halves clamped up, there should be about 25 thou endfloat on the cams. On final assembly, fitting the camwheels controls the actual endfloat. According to the T35 handbook, the camshaft bearings should have a running clearance of 2 thou, but it doesn't give a figure for the endfloat - I would suggest a minimum of 8 thou - a tight cam bearing can make a motor surprisingly sluggish!
Regards,
Eddie.