This is maddening! My sympathies.
Even if he got to find out the collector's value of the records, it could be awkward to sell them. A general second hand shop wouldn't pay much. Ebay or a main dealer, surely too much chance of being detected. Likewise trying to pass on in the fairly small world of Scottish soul-collecting.
How about focussing on trying to locate him, say by a local advert offering small reward, or using social networking sites, or by using a debtor tracing agency. I think you could get a trace attempt for a modest fee, possibly on a no-find no-fee basis.
Good luck.
Alan