The cam and cam gear get out of proper relationship with eachother any time the big bolt is loose so you need to pull the small plate on the small plate on the back of the head there are two holes on the back end of the cam and when they are level and the crank dots are lined up THEN tighten the bolts in the front of the cam. It may .be off a couple degrees but it will be close. The holder tool is the only way to get it prefect. Once the front cam bolt is loosened this is the only way to get it lined up. Tightening the bolt and lining up the dots without holding the cam still will allow the timing marks to line up but in reality it can be a couple teeth off.

I have warped heads milled all the time and have never had a problem.