Fat mustangs my favorite!!!!!
1st, Make sure it a real Mach1 and not just a sports roof with stickers. 3rd and 4th charaters in VIN should be 05 for Mach1 vice a 02 for sports roof.
2nd, Check the engine code 5th charater in the VIN will be a letter. F is for 302, H is for 351C 2bbl, M is for 351c 4bbl, Q is for 351C cobra jet, H is for 351C HO (Boss engine with lower compression) and is very rare.
3rd, options make the ride and there is a bunch for the FAT mustangs, heres some; NASA hood, Ram Air, A/C, P/S, P/B, frt disks, spoilers, stripes, deluxe interior, mach1 seats, comp supension, pwr windows, rear defroster, AM 8 track, factory Tack and gauges
problems; rust around tail light assmenblies, trunk floor, and rear quarter pnl wheel housings.
Old old Car Price Guide says a 1972 MACH1 #1 conidition is worth $22,000, a #3 car is worth $8,800 and a #6 car is worth $960
So depending on the conidition $7200 isn't bad. I've seen some pretty good cars for that price.