Aa guy on Ebay has listed a couple of high-wall ex-snipers for sale. He says they have the plugged holes for the mounts. I'm not sure what the going price on them should be, but he's set a minimum bid of $200.00. Might be worth it if someone wants to build his own; at least the base rifle you started with would be accurate...
edited: BIG OOPS!! DUNNO WHY I PUT EBAY; I MEANT GUNBROKER.COM