BOSS 429 May have been slow in your opinion but I’d still take one. The notchback mustangs never seem to get much respect, I get it I like the fast backs better myself. But I did have a 70 notch back with a 351 Windsor that embarrassed quite a few people over the years. I think the one posted may be a bit over priced, don’t really know any details, they could’ve at least washed it before they took the photo. My only interest would be to make a fast back car out of it and that would be cost prohibitive.
I would shop for another. You can get a pretty nice driver for a little more money. First 89K..it is more than likely 189K. Sitting is never a good thing for a car. Just to get that car put back together looking decent 10K, now you are into it for 22K. It is a standard mustang. For 22K you can get a 1967, running in great shape with working AC. I know because I am looking. Now if you get into fastbacks, GT's, GTA's, Mach1's, convertibles you start talking money. Sorry this mustang is not worth 12K, I would say not even 5K. Just my option do more shopping.