Just use a fan which plugs into a disc-drive style power connector. Formerly
very common, probably less so now, but you're looking for an old fan anyway
if it's on a 500MHz part;
Option B: try going fanless. Buy a big-ass heatsink for a Socket A chip,
run sans fan. Sockets 7, 370, and A all use the same mounting dimensions
(though supposedly slight height variations exist).