Not tired of this at all. It is all a learning experience for everyone. I have a click, not lifters, and have appreciated the other ideas put forth to solve my own problem.
Yes, the out of spec clearances could well cause a click. Maybe more that one click given those clearances.
The bad news is there is no easy way to adjust the so called double lock, lifters. It is a pain, and I got rid of mine in favor of the so called single lock, one nut lifter, after doing it a few of times. The good news is you can do it without removing the head or pan.
Using the Rule of Nines in Vince's Ford Garage site referenced above, you have to measure clearance when the valve (lifter) is down, and adjust it when the valve (lifter) is up. For me, I adjusted one at a time rather than follow them along as Fordgarage suggests. One at a time requires a lot of hand cranking, but better than losing track of which one of 8 lifters was up or down. I would lose track even writing it down. Up to you.
Anyway, using # 7 as an example, rotate the engine until #2 is up at the top. This will put #7 at its lowest point. (Rule of 9) Use #2 at the top to determine when #7 is down at its lowest because it is easier and more accurate to see when #2 is all the way up rather than #7 being at its lowest because #7 may be on the cam ramp and not all the way down. True bottom of the lifter travel is hard to eyeball accurately.
With #7 down, measure and record what the clearance is (say #7 .021). You now know you need to close it .008 to be at .013 (I would close it to .012).
Rotate the engine again until #7 is up at the top of its travel and the bottom nut and lifter flat are accessible.
Loosen the nut that goes against the lifter. You will need a thin wrench to get two wrenches on both the nut and the flat part of the lifter. Some grind down a wrench especially for this. Or you might find a thin wrench somewhere.
With the lower nut loose, holding the lifter with a wrench, rotate the top of the lifter with another wrench one flat (.007 per Ford garage) plus a "scooch" (technical term) to get the other .001 or .002. Then hold the flat spot on the lifter with one wrench and tighten the locking nut onto the lifter with another wrench. Watch out that the top does not rotate while you are tightening the lower nut. It always did for me, so you may have to eyeball in a small correction here. Rotate the engine again until #2 is at the top and #7 is at the bottom of travel. Measure the clearance of #7 again. If the Model A Gods love you, it will be just right. Repeat on the other valves. Its a pain, but there is the satisfaction of doing it yourself and learning about your car.
Let us know how this works out. Even if it does not eliminate the click, (not to be discouraging but it may be something else) your engine will be happier and run better. The valves will open as high as, and stay open as long as, they were intended to.
Good luck.