I got the shims out, and measured them as well.
Exh. 1-4 shims: 255, 255, 245, 245 - measured at 2.56, 2.53, 2.45, 2.45
Int. 1-4 shims: 270, 270, 270, 270 - measured at 2.68, 2.71, 2.71, 2.70
Measuring seemed harder than it should have been. There's a visible wear spot on the shim where it contacts the valve. It's visible only in that it's a circular spot. I cannot tell on visual inspection that the shim is dished at all. I tried to account for this by using a Lego with the stud in the spot (zeroing out the caliper on the Lego and then measuring the Lego & the shim). However, every time I used the Lego, I came out .02mm more than if I just put the calipers across the shim (disregarding the spot & possible dish).
I remeasured the valve clearance using another set of feeler gauges prior to going after the shims. Between the two sets I have, I came up with the following numbers:
Exh. 1-4 Valves: .20, .18, .30, .25
Int. 1-4 Valves: .07, .05, .07, .06
I suppose the next step is to order up the shims according to the chart in the service manual (page 16!), then turn my attention to the carbs. The plan thus far is to reassemble the top end, reattach the carbs (with new rubbers to the engine), see if she runs, and if I can get compression back. I'll see where I go from there.
I appreciate your input. Thank you.