Hi Matt,
I'm with Paco on this one. They're not as sought after as De Tomaso re-engined his Longchamp with a Maserati lump to create the Kyalami (allegedly to use up V8's), I think they may have been sold side by side. But whilst a nice car to drive and reasonably well appointed when you read about in the mags, a V8 that hasn't turned over in 20 years is deffo going to need a rebuild. The head gasket(s) will more than likely be shot, and the first time it's fired up (if it can be) will wreck the internals. As with all such cars theres a load of process to follow to prevent any damage, such as oiling the bores, or turning it over by hand or on the starter without the coil connected to build up oil pressure and circulate it everywhere.
But the best way would be to take it apart and assess as firing it could cause damage that could make it a write off (especially items such as the crank). As per the link Frank sent for a mint running car up for around16K, a full V8 engine rebuild is currently costing me around 10K and the engine is not together yet so it's likely to go up. Therefore that leaves you 6K for the remainder of the car, not a good balance sheet. Whoever takes it on will be letting their heart rule the head unless they buy it at the right price and do all the work themselves.
My advice would be to see if you can turn the engine at the crankshaft pully (big socket and torque wrench, (can be made easier by removing the spark plugs), but then to leave well alone if you are not confident with the mechanical aspects and sell it as what it is the proverbial barn find but not with a siezed engine. If it's siezed, then only those experts int he field, or if you're lucky an engine (it's a wet sump unit) from Eurospares are the only options. But again that has it's associated costs which you may not want to incur.
I'm not sure about ownership laws, but since it's been stored on your site for so long just apply for the V5 and you will probably find that the DVLA will issue it to you in your name. (They do try to contact the previous owner but only give then a short grace period). Once you have the V5 in your name I should think you could sell it on, though an one with better knowledge of the workings of the law may be able to clarify this.
By the way, where abouts in the Midlands are you as I'm in Brum ?