Unless you get super lucky...you'll never get the money out of a car that you put into it...especially when you factor in your labor
I don't think 15k isn't out of line for a 70s vert depending on numbers match, build sheet, condition and options.
I recommend you take lots of pictures and post them here and I'm sure several members will let you know their opinions. Make sure you check the trouble spots (the floor, trunk pans, fire wall, frame rails, around the cowl, etc).