A friend of mine called me today to ask about the bike pictured below.

He has an option to buy it, and whilst he's had a lot to do with bikes, he hasn't been into Ducati's up until now. He called me for some advice, but my knowledge is restricted to twins - I know next to nothing about singles. The bike is a runner and is currently road registered. The condition seems to be best desrcribed as fair - but I'm only going on the photo.
It is being presented as a 1974 350 Mark 3 (not desmo). The frame number is DM350GT 15005 and the engine number DM350 15005. On the little bit of research I've been able to do I wonder about the following:
- The tank looks like the wrong one based on photos I've seen?
- Are the side covers right for this bike?
- The seat looks like the wrong one?
- Should it have a mechanical tacho drive on the cover?
Any comments would be most appreciated on these and any other thoughts you guys might have. Also, what price range would you put on the beast as is, and what does a good restored example sell for?
Kev