I would say $4500 for a good clean pilot is a good price, you might find it for less, maybe willing to pay more. $6000 seems too high for this but you have aftermarket shocks add ? $500, extra pipe you might be able to sell for $200? nerf bars and front bumper, if they have value to you then $300?
You will have no idea what condition the
Engine is in, even if the compression is good unless he has receipts for a complete rebuild the bearings could be 25 years old.
When someone tells you it will do 75 mph no problem you have to wonder what other BS he is telling you.
you asked for my opinion, if it were me I'd think more in the $4K area provided the Engine and trans are in good condition, you do not want to pay top $ for a money pit.
I'm sure if you are willing to spend $6000 for a pilot there may be someone on this site with a reliable machine that they may be willing to part with, Mud?