Max, The noise you've described doesn't sound like any valve related noise I've ever experienced.I think you're going to find a more major problem giving a noise in relation to the valve movement described but, I hear you say the pan is off , take an extra look at the big end bearings.You say the click can be felt in the crank/pulley--observe the big ends when this click happens for unneeded clearance.Tap the big end side to side on the journal looking for differences in tightness- a bearing in deep trouble at one stage actually wll be too tight as the thinned out bearing shell climbs up on itself-the end is near when this happens.Look for signs of more heat on one rod than the others caused by the failing bearing tightening up and cutting off the oil supply.Look in the oil pan residue for material thrown from a failing bearing in line with the "throw off".
Also be suspicious of the piston pin area when this click is heard-these old pistons come apart in the strangest ways and many times get noisy when the piston is in a certain position.I once witnessed a cast iron piston in a 216 that perfectly broke off the piston head at the bottom ring groove--when the head was removed, all cylinders looked normal but the piston in the bad one didn't go up and down the detached piston head just stayed on TC.
If a valve were this tight in the guide it would probably would bend a pushrod and you would have found that.
Good luck
