For a track bike I would go for a something that is not cosmetically mint... but get a 996 instead of the 916 .
I used to have a 916 trackbike and you are so getting hammered by the 1000 IL4 in the straights. Even some 600cc actually. The 996 has quite a bit more power.
High mileage, not necessarily a huge problem, as long as the bike has been regularly ridden. I took a ST4s to 40,000m without huge issues. But that was motorway mileage with commutes that would be 60miles+ a go. If the bike has been ridden only on short journeys, the whole valve train, etc would have worked cold more and probably suffered more.
That said, the thing I loved about my 916 is that I could ride her on the absolute limit. Since I got a very powerful 998, you really have to recalibrate your brain.