[Davescort97]

The hot brakes smell could be the clutch disc slipping against the pressure plate. Prognosis---new clutch. The speedometer gear operates off the final drive differential gearing. If the speedometer is moving when the car is in gear with the clutch out, there would be some cause to suspect the differential is turning, but the half-shafts are not. Side gears that turn the half shafts could be stripped out. Prognosis---new tranny.
I'd put in a boneyard tranny with a new clutch kit. Rebuilt trannys are running about $1200. You probably paid less than that for the car. I think you would be looking at about $400 for a used transmission. The older GTs were fast movers. I hope you get her going.