I'm a fan of inexpensive current-production CNC alloy pulleys with dinky little cartridge bearings in them. They last a long time and are quiet, too. Sometimes you might have to ream out the inner "cups" to let the bolt pass through, but that's no big deal since they're soft aluminum.

I've never tried them in _this_ derailleur, but if you're willing to do some filing/reaming on the cups, they should fit nearly anything vintage.