Difficult to say really. Long history doesn't necessarily say its been really well looked after, just that someone has kept the receipts.
The car is going to be 20+ years old, parts will have to be replaced anyway - its irrelevant if a clutch/gearbox was changed 10 years ago.
Detailed short-term history, would usually show a really mechanically, well maintained car. I would probably say 3-4 years of GOOD history, is worth a lot more than 20 years of MOT slips and service stamps, as that will be indicative of what major service parts are due/or have been replaced.
The main issue is body itself. You can have a detailed FSH, but if the body is rotten - its not really all that relevant, especially since parts are so cheap.
