Beautifully built bikes. The last of the really handmade style. I would describe it as a burly beast. I gave one up in favor of my 03' 501only because the 03 handles better. The earlier bikes are more crude but very special I say. Ive heard that with modern forks they can handle much better. In terms of a collectible vintage bike, I predict they will really be something. But all Bergs are like that I guess. A unique feel. Tough.
Take the valve/rocker cover off and check the cam and rocker bearings. Use KTM sealed bearings on the cam if the stock ones are sloppy. Thread on a new timing chain with a clip style master link if you are wanting to make absolutely sure its all good. taffmeisters.com sells them.
Or, just put a couple squirts of 2 stroke oil in the cylinder through the spark plug hole, some fresh oil in through the valve adjust covers and fire it up!
Fresh oil change and valve adjust as soon as you can of course. These are all "the norm" stuff though I guess. Just don't ever run any top end parts that are questionable. Ever. Ask anyone here, the top end has to be tip top or else!
I am jealous of you tho. Post pictures!