I forgot to mention that the fork tip slots on my Varsities is only wide enough for a 5/16" or 8mm axle, and seems to be set for only 96mm hub width on the older one.
I filed away to get the QR 9mm axle to fit, and beveled the bottom tips so as to make installing the 100mm width QR hub much easier.
"...And more or less leave the rest of the bike as it is."
I would, as a very first upgrade, install a modern, narrower chain. An 8-speed Shimano chain will work so much better on the French or Italian freewheels, and 9sp chain works best with Suntour/Shimano freewheels (or with any cassette).
Even the $10 WalMart/drugstore Bell/TaYa "Speedy" 8-speed chain makes quite an improvement.
I've put in many hard/fast/hilly miles on a basically stock, 39-pound Varsity, a big one with no mods other than WTB saddle, 9sp chain, 90mm stem, brake pads, Wellgo SPD pedals and Suntour 6sp freewheel.
Alloy wheels and parts and lined cable housings would be logical next improvements, and of course anything like a dented rim also gets priority to be tossed.
Of course, most Varsities firstly need a few hours of TLC.
A smaller open-end wrench, filed out to the needed 14 and 16mm (9/16 and 5/8") for the axle nuts, can be reasonably light for carrying in the bag, compared to any adjustable wrench.
Sturdier wrench is 49 grams, vs. 57 grams for the cone wrench, which also does the job if the axle threads are well-lubed.
