Another way to check valve to cyl clearance would be to put checking spring on #1 ex valve. Set valve lash to 0. Rotate crank to gain full valve lift, then push down on valve until it contacts cyl. You can put dial indicator on retainer and tell exactly what the clearance is. No better than gearheads suggestion, just a different way to do it. Stock valve size will allow .650 lift with pass. block, but once you increase diamiter, it hits the cyl sooner resulting in less clearance. Most suggest .100 minimum clearance but I have used .055 with no problem. Seems like even less would be safe. Not like the piston chasing the valve or valve chasing pistion, but I guess we need a minimum to go by.
Watch out Fred, here I come!
