I have to say I am a fan of the older Taylors. I have a 1985 (Lemon Grove) 550 which is appointed close to the same way as that one except for a Martin style bridge. I also have a 1989 K22 and recently sold a 1988 K20 (both Santee). All of them had thinner necks compared to newer Taylors I have played.
IMO I think that is a steep asking price for a 510.