I emailed the guy about the car and here is his reply:
The inside floor boards and interior needs to be replaced from front to trunk. And yes the interior is from my wifes 71 Mustang. Her 71 Mustang was rusted so bad that the back differencial came through the trunk floor. I changed it all over in 1980 because my wifes interior was in better shape than that of the Sprint. Unfortunately I wasn't aware of what a Sprint was at that time. I was a Chevy guy and didn't check into it. I believe the frame rails are still in good shape. Can't really tell until the old flooring has been removed. As far as the engine goes I ran the car for about 13 years until it started to have a ticking sound in it. I am not sure if it is a tappet or a connecting rod cap. I believe it is the later so I stopped driving it until I had time to pull the engine and tear it down again. When I did the restoration in 80 I replace everything in the engine to new parts, forged steel M4 crank, "K" cam, anti-pump lifters with adjustable push rods, new pistons and connecting rods and valves. The heads were reworked by Summet Auto Racing Co. and has brass valve guides in them, so I could use unleaded gas. And I don't believe there is more than 30K on the engine. But I drove it hard when it was running good. The car had almost a 100K on it when I bought it and it was an original Oaklahoma car. But I bought it in Ohio. I used good Valvoline oil in it so all the parts should still be good. I wanted to tear it down but never got the chance. So if no one buys the car I just might do that to make sure it is OK now that I am retired and have all the time in the world but no money. When I was working I had the money but not the time. Aint that the way it goes? I feel that this car is well worth what I am asking for it and who ever buys and and if they do a complete original restoration on it, it will be worth a lot of money. It will be one of a few Mustang Sprints with a 351CJ engine and C6 transmission put into a Mustang Coupe, which there were only 90 originally built. My car was built in April of 1972. And that was the last month that they built any. A total restoration is going to cost several $1,000 of dollars but it will be worth it in the end.
I hope this answered your question.
Sincerely
Gerald McClellan