the 788 in 6mm is getting harder to find, becuase of the longer bbl length. But that is too much money. I would check it out thoroughly especially the trigger; if it is factory, and has been sitting around a long time, I would ask to take the rifle out of the action so you can look at it. Also when you pull the trigger, it should have a superfast locktime, with no creep or crawl whatsoever. If it does have any creep or crawl, then it is getting warn from sitting in oil/cleaning fluid too long, without being cleaned/dried out. So if the trigger is great, and the rifle is in great condition, and the rifle has both of the origional front and rear site setups; i.e. the rear step/stair sight, and the huge front shark fin sight. I would not take this rifle if it is not almost perfect. But if it is in great condition, and has all the above goodies, then 500 may be worth it.
Now then, you can get a drop in Timney trigger for these, which are fabulous, and since you have so many great 6 mm bullets out there now, you could get some 105 or even 110 grainers, and shoot laser shots with this out to 500 plus yards easy, and with the super long case neck, it is not as bad a throat burner as everyone thinks; just don't heat it up by shooting too fast.
Just as a final thought, I have had a few of these in the past, and now have settled on my 243.
I never had a bad one, never had one that wasn't accurate, and never had one that couldn't
absolutely startle me, on how fast the trigger lock time was. if you want it, and again, has all
the stuff I mentioned above, then 500 bucks ain't to much.
that scope is proly either an old weaver, redfield or burris; could be an old Japanese made bushnell
or Tasco, so if it is Japanese made, don't fear it-- it will be fine. I stripped my stock down, and
redid it, in a nice honey color, with several coats very thinned out with mineral spirits. Came out a
very nice looking rifle.