Magnum Swap balancer w/LA timing cover. Marks?

Hey Rob, Does he have to pull the rocker arms so the valves don't open and close? The piston stop points towards the exhaust valve and I just bent the living crap outta a Chevy small block exhaust valve a few months ago doing the same thing with a piston stop.

I just stood a 6 inch section of plastic tubing on the piston and turned the crank back and forth till the tube started to move and divided that in half at the balancer.
Different ways to skin a cat as they say.