NOS Continental generator belt

I just picked up an NOS 1050mm generator belt, an official VW part stamped with a logo and part number (311 903 137). It only fits VW 1500s up through engine number 0 141 841 (December 1962), when the size of the crankshaft pulley was reduced to lower the generator RPMs. I realize "rare fan belt" is kind of an oxymoron, but that's just what it is. If you're restoring an early engine you've gotta have one.