One possible reason for variations in peoples port timing numbers could be caused by the cylinder not being aligned perfectly over the center of the crank, so the numbers are different depending on BTDC or ATDC.
I've been measuring both ways and averaging hoping to compensate for the degree wheel being slightly off of perfect TDC alignment, and found on my 026, the intake number was the same before and after, but the exhaust had maybe a 2 degree difference, and the transfers a 3-4 degree difference. The results were always repeatable.