Check my work-Chime in please

Ok, my cam is in the engine and degreed in where it is supposed to me. My double row comp timing set seems to have a little more chain slack than I would like but--------. I am now ready to check piston to valve clearance but am a little unclear on how to do it. My heads are together with valve springs decked and installed. I was thinking installing the left head and putting lifters & pushrods in #1 only, installing head and spinning it with clay on top of the piston. I get a little hazy after that. Dont want to bend anything! Could use a little good FABO advice here, the search didnt turn up anything definitive.
TIA to all, DR:coffee2: