Cam degreeing help me understand!

How are you trying to find TDC? Use a piston stop. That's the best, most positive way.
I was thinking the same. I am no expert and I usually run mine dot to dot, but I did this in tech school many years ago and I remember using a piston stop that bolted over the bore. I suppose you could temporarily bolt the head on and use one in the spark plug hole also.