Thank you all for the responses so far and the guidance. As I feared, I do not know enough (yet) to ask a question that is focused enough.
In example, Mepearson - You asked me about TP type tapes versus 7.5" 4 track tapes, or both. I don't even know what TP stands for. Guessing that 7.5" refers to the diameter of the reel. Guessing that "4 track" is an example of how much resolution the recording process affords . . . I suppose the capacity to play both types increases the chances of finding more high quality recordings. If so, that is appealing, but of course, that likely also increases the price.
In example, Mepearson - You asked me about TP type tapes versus 7.5" 4 track tapes, or both. I don't even know what TP stands for. Guessing that 7.5" refers to the diameter of the reel. Guessing that "4 track" is an example of how much resolution the recording process affords . . . I suppose the capacity to play both types increases the chances of finding more high quality recordings. If so, that is appealing, but of course, that likely also increases the price.