How to find tdc

MAKE SURE the plunger is RIGID.
I agree. with you getting 8 & 10 degrees then yes the dampener is 1 deg off (fairly common) but do confirm everything is rock solid. I've been racking my brain to figure out which side of the OE slit that (1) deg next to it is true TDC but I ain't grasping it (yet). & I will concede that if you are going further & degreeing the cam (always a good plan) then the wheel is a good plan.