It might be a good "parts car" but one hell of a project to make right again. Even if the head could be milled true and the block wasn't damaged, there might be more wrong that just that. The trunk lid isn't such a big deal to replace, but getting the roof straightened properly might be a real hassle depending on how damaged it is.
Another thing, you might ask the guy if it has been "totalled" by an insurance company. I once bought an old Malibu that was "totalled" (which really just needed some front-end work) and it became an issue when I went to get it registered B/C it was listed as totalled by the insurance company. Might be different where you live... Texas seems to be kind of jerks about things like that.