Using the Wallace calculator, even assuming the valve is closed for the full 180deg of the compression stroke(which is saying the lifter bleed down makes the cam 132deg shorter), it still only showed 212psi.
Even with the lifters fully collapsed, I'm not sure the intake closing point would change by 66deg.

I'm pretty confident the lifters are at least partially collapsed, but not enough to add 100psi to the compression test.

I think there is a good chance the gauge is reading a little happy.