Help! Swapped 302 heads on my 318.

I agree with most of that but hydraulic lifters are pretty forgiving.
I have never had the problem that the OP has had. I'd have to have it in front of me to have a better shot at fixing it.
Maybe something like this:
Remove the valve covers and have someone slowly rotate the engine until # 1 cylinder intake valve closes. Then back off the bolts to the rocker shaft. IF the valve tip rises, the pushrods are too long. Try the same with other cylinders THis would indicate that the resurfacing of the heads may have exceeded .030 which is far outside the tolerances of hydraulic lifters.
Of course, a head milled that far should also have intake fitment problems but...