Dear Randy;
Drew is correct in that; the intake valves (if there hit) just get pushed closed ahead of time, bending the pushrods involved.
The head can stay on.
The front main cap needs to be drilled/tapped to do that, along with the holes inlarged in the timing cover.
This isn't really helpfull though. You need to be able to "guide" the cam in/out to protect the bearings etc.
It was done on racing engines to advance/retard the valve timing in 'days gone by' when a lot of experimenting was in progress.
Like he stated "the valves should be fine"...
Good luck.
PS: If your using an aluminum cam gear for replacement; both (gears) must be replaced and don't damage the 'lock plate' as; it needs to be re-used. (lock washers won't work).
