One of my brothers had an R5 which was similar, the earlier version, piston-port, no reed valves. I liked to borrow it, pretty wheelie-prone.
I had an H1 Kawi that was a lot of fun, not as-good handling as the R5 Yamaha. I loved to embarass the local Harley guys on it, even two-up you could walk nearly any Harley "built" for performance. They hated the two-strokes but they sure couldn't beat them! One of my friends bought a new Sportster 1000 the first year they became available, and he was pissed his new Harley couldn't beat my older two-stroke with 1/2 his displacement!
One thing for sure, I would want to see what's inside the box before I agreed to pay for it. I recall British Only in MI was selling a new BSA Gold Star (pretty-sure it was), still crated, and they had X-rays of the box to show there was a bike inside. X-rays or not, before I paid the price, I would want to confirm there was a new-old-stock bike as was advertised lurking in there.
A local Yamaha shop had their franchise pulled because their crates in "inventory" at the shop were filled w/junk! They were uncrating them, removing the bikes, and selling them out of the country, and filling the bike crates w/junk, re-assembling them, and having them stockpiled in their storage area for inventory. The factory distributor got suspicious, pulled one out and found-out the truth.
More stuff on crated bikes:
http://www.classiccyclespares.com/