I've stretched the Cane Creek hoods over the fat adjusters and it fits and looks good. The ones that I cut off looked terrible.

There will be a lot of friction created by the tight-fitting rubber when you try to turn the adjusters, but a tiny bit of silicone grease (Shimano/SRAM cable grease or faucet/dielectric grease) goes a long way toward easing the torque required. Just don't use petroleum grease is my recommendation. Also, the tight fit eases over time.

Schwinn levers from this era almost always had adjusters, so the originals may have been swapped out for a pair without aux levers(?).