Do you know how many socket 7 heatsinks there are on the market? Get one and fit it on your card yourself. I'd suggest a newer Socket 370/A HSF
I know you're probably gonna ask how to mount the HSF, so here it is:
1) Arctic Silver Thermal Epoxy or Arctic Alumina Thermal Epoxy
2) tap holes in the heatsink and mount with nylon nuts and bolts.