from my experience i would say stay away. he has taken it apart of lost stuff and forgoten where stuff goes. i would rather have a seized motor than one thats has been torn apart and kinda put back. also the difference in a $500 bike and a $750 bike is alot, chances are the $750 will be cheaper in the long run..
for instace i am fixing up a 92 vfr750 this winter, it cost $1000. but all it needs is a real good cleaning a paint job and some body work.
before this we pulled in a 86vfr700 needs everything, forks are bent sub frame bent R/R bad tires,chain sprockets,oil cooler, radiator, body panels suck.etc.. so unless you are really really good, save up just a little more money and get one in better shape, unless you never want to ride it, and just work on it for ever.