how to check piston to valve clearance?

Shortblock has to be assembled, including the cam. You have to get checker springs (cheap and probably easy to find) and then get the valve springs off, and put the checker springs on. Then bolt the head on (we did it with no gasket, to be sure) . To note, before bolting the head on, place some clay on the valves or on the pistons (we used the pistons, idk if using the valves would even work), then bolt the head down, and rotate one engine cycle. Also set it to TDC before starting, and use the number 1 piston. Thats an easy way to set it up right. Now Im not sure if its recommended to do it on all the pistons, or whether they will be set if you check just one!