SMPTE LTC has no dependence on the tape decks you are using.
They simply carry the ‘audio’ as a spare track, and record or play it exactly the same as any other track.
All the timecode gear is external to the tape transport (unless it’s fitted as an option).
The only electrical connection between the timecode equipment and any transport(deck), is the ability to push or pull the capstan servo to aid in synchronisation.
One thing to keep in mind, is that as a high-modulation analog audio signal, there is high risk of crosstalk or leakage between channels/tracks.
EDIT add: The raw LTC signal when it leaves the ‘generator’ is usually between 0 and +6dB (0.7 and 1.0V p-p) as a square wave!
This ends up being naturally rounded and clipped by the capacitance of cabling and electronics limitations (not to mention the tapeitself), so your reader/decoder should be designed for significant signal loss and shape/peak degradation.
It’s not rocket science, but needs to be designed.
Also, consider that the nominal 2kHz stream goes well out of the audio spectrum when spooling/shuttling the tape. Hence wideband amplifiers etc, but the decoder also has to figure out how to handle these surges well over 20kHz when moving the tape.