I'm not sure what DK Money is but it sounds like you may be thinking of buying this car long distance. If this is the case "BUYER BEWARE". At the following link there is a good article that you should read if you are buying long distance.
http://links.carjunky.com/cgi-bin/cars/jump.cgi?ID=1660.
The price sounds pretty good. But beware of structural rust. I have seen some cars that look fantastic on the outside, but I would be scared to drive them because the frames were so rusted. I'm not to familiar with the late 60's mustangs but I know that the earlier mustangs had a tendency to rust in the floor pans, at the rear leaf spring purchase points, on the point were the frame enters the body just behind the front fenders. If you can get under the car with a flashlight and give it a real good look. As far as the floor pans go, I have actually seen people go as far a tapeing rust holes up and then spraying an undercoating to hide the evidence. As far as the engine goes, who really cares. You know that its not original. If your happy with not having an original engine then that is what really matters. You are buing the car to drive and if it runs then great. Good luck