Outstanding finance on ST70

I'm looking to buy a 1970 St70. I did an HPI check with MCN and it came back with finance owing. I've contacted the owner who claims to know nothing about it. The bike has no v5 but is still listed on the dvla web site, which says it was last taxed in May83. My questions are, should I buy the bike? Would the finance company have written off the finance after 20 odd years? How can I find out who the finance company is and would the DVLA issue me with a V5?
Any suggest would be appreciated.
Thanks
Scot

If I were you I'd look for another bike.
Too much hassle,