Stepdaughter learning how to drive a 4 speed

I have a bit of a dilemma that my youngest daughter wishes to learn manual trans. I have an '03 Ford Cobra 6 speed. A '07 Ram 3500 dually diesel 6 speed. And my '69 GTX 4-speed. The truck is big. Thus not the best for a newbie. The Cobra is heavy clutch pedal and tight gear pattern (The hardest to drive.) The GTX is easy. BUT MY GTX??? 4 years ago the 3 vehicles were simular in value. But we have all seen what has happened. Especially in the B-body world.

What to do? (She wants my GTX.) lol.
We have been practicing in a ex Sears parking lot so there is a ton of open space, she just needs to pay attention to the light poles, lol, but we will continue doing that until I feel she is ready to drive in traffic.