valve clearance

[budget300zx]

Ive done a bit of researching on this topic and have not found a definite answer.

does anyone know where i can find the piston to valve clearance on both a N/A and a TT?

the machine shop had to shave some off to level the heads i just received and i wanted to get some info on how much can be safely shaved off a tt head going onto an N/A engine. Im sure the N/a Pistons are "taller". i could check this with clay/playdough/ect. if it will be tight but would prefer not to go through the hassle if possible.