The 72-73 Montego GT is based on the Torino body, so I don't think they would work.
I really don't think that 'Tiger' is too far gone to save. You already have the new engine goodies, your interior is near mint, and the rest of the car doesn't look all that bad except for the quarter panels. Since I don't know about your financial situation, I'll just say that rust-free quarters can found out west. I found a pair in Las Vegas for $300. The only problem is getting them across country. They are so large that they have to go truck freight, and that ain't cheap. The shipping was gonna run me another $500-600. Maybe its time for a road trip. Find the parts you need, then rent a u-haul trailer.
I have a guy on my mail route that goes out to his place in New Mexico several times a year and brings back MG cars and parts. He just brought back a solid, rust-free MG Midget body. I told him that any time he has spare room on his trailer, bring me back some Cougar sheet metal for our 71-73s! He's going back out there in a couple of weeks. If I could get a pair of quarters w/outer wheelhouses for $400-500 delivered, I'd be a happy man!
I have to agree with Cougrrcj, the cat is definitely worth saving. In fact I have two rust free front 1/4's, both need to be painted but it would be cheaper than a new car. Also if you check w/ a body shop they might be able to offer a quick fix on the cat.
Take her to a body shop and ask for an estimate. See what the price difference is with them repairing the existing metal versus you supplying the quarters. Estimates are generally free. Just get it in writing before (if) you give them the work.
I have been quoted $1000.00(from 3 different shops) to hang the 1/4's if i supply them thats not including the paint work! Add in the cost of rust free 1/4's and i am looking at about 1800.00 just for the metal and attaching. Now figure in body work and paint and repair to one if not both my wheelwells and my trunk. I am looking at around $3500.00 invested into the back of the car alone, add in the fact that i need my passenger door replaced or repaired, and my front fenders repaired i well past the point of a new car. I would rather see someone who knows what their doing bodywise to take the car and fix it then have me blow 5k+ on her and have her not even close to finished.
I have weighed my options adn if noone buys her then i am going to have to part her out.
It's a sad reality i have to deal with.
Have you ever thought of just diving in with some online coaching and doing the patch yourself? Patch panels may be available (I have no clue) or may not. Either way, you can't mess it up any worse than it sounds like it is by taking a grinder and a rivet gun and sheet metal and a welder and bondo (a little) to it, can you?
I say dive in. You have nothing to lose if the car is that bad. And everything to learn.
Be careful there, you can get a lot done that way. After taking that same route, I'm now positively adequate with a welder. Of course, rust buckets seem to have a natural attraction to me too. Seriously, he is right. Worst case is you spend a couple hundred dollars, fail to save this one but learn how to do the save the next one. And you still have the stuff from this car, which means you could buy a straight, solid car with a blown engine/tranny for cheap and transfer your good stuff.
I tackled my 70 standard when I was 15 years old. The body was straight and only had a couple of bad places, but still...I didn't have a clue when I started. A year later, I took it to the paint shop in at least 100 different colors of primer. And it was straight.
Now, I have it stripped and sanded again and in about a week I'll be spraying on a coat of primer to get it all smoothed out for paint.
I'm now fixing stuff that I let go for too long...I was busy buying hot rod parts.
In fact, I can take some pics and write up a little essay on patching panels for you if you like...but then, Mustang Monthly probably has eleventeen articles on bodywork written by people who know it better than I do.
Just don't let bodywork scare you. Besides, what may look like a complete replacement of a quarter to you, may only be a patch panel away from acceptability and paintability. Only the grinder and D/A sander will tell you that.
However, from your posts I'd say that on top of being a decent and sensitive person, you're also a tick on the bright and capable side.
Whatever you decide, It's your car. Part it out or sell it and you may or may not regret it. Fix it yourself and you may love it or hate it. Noone knows but you.
Do what you have to do. You know you always have a forum full of people who will support your efforts.
Damn Kraven, Well i am cetainly moved by your words of encouragement. I think tomm i will go out and assess my situation a bit more before i go all sell/parting happy. Besides my car is not doing to well on e-bay