Someone 5' tall should be on 26" or even 24". I cant imagine the geometry compromises not to mention toe overlap with a 29er.. but anyway, about you.

Forget about using parts from the stumpy. Fork is incompatible and the drivetrain is too old to bother.

It is possible to build a HT bike with an eventual move to FS in mind. Fork travel is one of the things to look at. Make sure both frames are compatible there. Certainly they would need the same BB type and same head tube.