My friend does most all of my cyl head machine work, but IIRC, if you go about 300 lbs over the nose of the cam (spring compressed), you would need screw in studs. I can ask if you need a more definate answer.
An old trick to do was to just drill & pin the factory studs. (Not done so much anymore)
I have machined for screw in studs while the cyl head was on the car by a hand drill & the correct cutting tool( not optimal mind you) but I had done it.
Any competent shop can do this for not much money.
