I'd certainly be writing to DVLA asking for a log-book, google DVLA and there will be a form....
The bigger issue is that there is a little (illegal) industry of putting the vin plate from older wrecks onto newer vehicles - usually 90s - and selling them as "tax-exempt". Doing so or buying one runs the risk of having VOSA pull the vehicle and scrap it. Now, I don't know how often that happens but the risk is there. Less risky would be putting the plates onto a "bitsa" built up from a wreck and parts from other vehicles. Strangely a new chassis can legally be used but an old chassis can't, it retains the ID it had originally.
To stay legal your best option is to get your Uncles vehicle and rebuild it on a new galv chassis using as many original parts as possible.Google DVLA and rebuilt vehicles to see chapter and verse. Try Ebaying a Series 2A ID and plates on their own and you'll have a couple of hours till someone reports it to Ebay as "promoting illegal activity" and the ad is pulled.
....the other option is to sell it as project. Surprising the number of people who might be interested.
Cheers, Gene
( Series 2 Club area rep )