A GI scope base will be another tough one. The best bet IMO is a WTB ad in this forum, CULVERS and Gunboards forum. A few years back there were some loose spare floating arournd. They Redfield Jr. bases that had been packed or supplied by Lyman during the Korean War. Parkerized but not marked "REDFIELD". Some one may be hanging onto one and just may decide its time to turn it into cash.
Two things are working against you i am afraid.
1. Several years back the govy released a number of A4's w/o bases (the so called Grade B's). A number of these have been restored by now.
2. The vintage sniper matches have also increased the demand.

But good luck.
Too bad about the Sarco stocks. The ones I looked at were pretty nice.

Regards,
Jim