Submitted for peer review...
With my current chain length I get a little resistance here:
With the wheel further back it was enough resistance that I wasn't comfortable with it. With the wheel where I have it, I can feel the spot but it clears the cog teeth with some room to pivot still left in the derailleur. Since I don't intend to use this combination, I just need to avoid catastrophic failure. (And, I've got some experience with the results of a chain that's too short, so I do know how catastrophic the failure is and how quickly it happens.)
Once the chain is on the big-big combo, it looks like this:
Obverse:
Not pretty, but I have not exceeded the derailleur's natural range of motion.
Small-small is not so good:
As soon as I start turning the pedals, it takes up the slack in the upper part of the chain, lifting it off the chainring, but when the pedals aren't turning I get the above result. I'd need 28T wrap capacity to make that work, so I'd judge that the Super Record derailleur does not have 28T capacity.
On the 32-15 combination, the results are much better:
So, that's 26T wrap capacity (49-32 + 24-15).
Finally, the finished product:
I'd rank the offenses to tradition that I have inflicted on this bike like this:
1. Clipless pedals
2. Modern compact handlebars
3. Non-coil cable housing at the rear derailleur
4. Absurdly long valve stems
5. Tall stem
6. Triplized crankset
7. Modern clincher rims, polished silver not dark anodized
8. Brake cables too long
9. Not period correct bottle cage
10. Quick link in the chain
Others may, of course, order this list differently or spot things I've overlooked.