[blykins]

Most builders use that method. I use it in addition to the clay.

You'll find that the closest clearances are going to be in the overlap period of the cam. I start checking 15BTDC to 15ATDC. Your exhaust valve is going to be the closest BTDC because the piston is chasing the exhaust valve down.

You won't be able to open a valve with the stock spring on there. You'll need a set of checking springs.

I check both valves on #1 cylinder by putting the pushrods in and using a pair of checking springs. Mount your dial indicator. You set your lash and let the cam open the valve. Check it every 5 degrees of crank rotation. When the cam opens the valve as much as it's going to, zero your dial indicator then take your hand and open the rocker arm while watching the dial. When the valve bumps the piston, then note the reading.

You should also clay it up to check radial clearance. Depth clearance isn't all there is to it. Sometimes the valve relief tapers down and the valve will get closer as it opens up more.