Piston to Valve Clearance

Hi,
I may have a problem with my engine combo. I have a 77' T/A block. Flat top pistons with vlave reliefs. On a 72cc head which is what i got 10:1 comprestion. There #62 by the way. I have no decking on block or planing of the heads. Bottom end is stock specs measurements but I am concerned about my piston to vavle clearance.
Now I have just bought a hydraulic roller cam with .509 intake lift and .528 exhaust lift. Now I also purchase 1.65 roller tip rockers as well. My problem is that I do not have the heads assebled yet and would like to check my clearance if I can either through specs or measuring now with out attatching hardware first. These rockers will give me .524 intake lift and .543 exhaust lift. And I'm gonna assume that the piston is .001 down in bore at top dead center.
Has anyone have a engine combo that is similar or does anyone know how to check now during my build up instead of machinging the heads and doing the clay method? Any comments are great.
Thanks

Clay. Just set a head on the block. Push the valve down onto the head about how far you think the spring will be compressing, you may measure this in conjunction with the cam lift and if the valve is smashing the clay, and making contact with the piston or close to it (a few thousandths within) then you may be pushing it, but otherwise you are all good. I have had to do that on a few rebuilds were we were using aftermarket parts, i have never had a clearance issue but i always did that just to check and make sure.
Jake

Hey,
Has anyone have a engine combo that is similar or does anyone know how to check now during my build up instead of machinging the heads and doing the clay method? Any comments are great. Engine specs ae in an earlier post.
Thanks

Engine builders use computer programs and blueprints for things like that. Not exactly things that a DIY'er has access to.