Oh one more thing. If that Ninja has stock gearing, going up one more tooth on the front sprocket will make everything a lot better. The older Ninja 250 was one of those one in a million bikes that really was undergeared. Going up to a 15 tooth front sprocket will help on both the top end and the bottom end. It's better everywhere, no sacrifices anywhere.
I won't spend more on a bike than I think it's worth, but if it's a good deal, I don't seem to have a problem buying bikes I don't need.
2002 Vulcan 750, 2013 Royal Enfield B5
2001 XT225, 2009 Genuine Stella
1980 Puch moped