Solutions for too much compression

So I took off the drivers side valve cover and turned to motor over by hand. Had a friend watch the rockers and as I passed 360 degrees past tdc ( where the exhaust is just closing and the intake is just opening )I had him tell me where exactly the exhaust fully closed and the intake just started opening. I looked at the timing mark and the piston was exactly at the top. I repeated this several times to make sure he was seeing it right. I got this idea from another post on FABO and it made sense to me.

That might not be accurate enough especially with hydraulic lifters, and just eyeballing the dampener as opposed to actually having it degreed / or degree wheel. ALSO has the TDC mark been confirmed with a piston stop? You know how to do that?