WVE (Wells) 6D1025
https://www.rockauto.com/en/moreinfo.php?pk=2063984
This is a hardened gear (click the part number at the upper right, all those applications were steel roller cams). Comes as .431" shaft size, buuuut.... if you have a lathe and know how to use it, it's easily bored to .491" or .500".