Steve's answer
"Only thing you can do is calculate out the math to make a new pulley.
I think the guy has a VPI Scout, so 11.5in platter w/ 600 rpm motor. So he needs like a 1.495" diameter pulley for the 78RPM.
Cutting to 1.5" diameter pulley will probably be ok too. Will end being 78.2 RPM but that's ok."