If you want to dabble in it, start with 1/4", Technics are all great, 1500, 1506 and the 1700 are great decks, the difference is 2 vs. 4 track and auto reverse, a Tandberg in good condition you cannot go wrong with, Otari makes a good deck, but I would not start with that deck unless you know that you r2r is want you want to get into. They do make plenty of 1" decks, but they are not 2 track, they are all multi track and unless you plan on doing mixing, etc, are way beyond what you need. As previously suggested, I would look on the vingage r2r site from Texas, he is very knowledgable and helpful. You can ask him questions directly, he monitors the r2r forum on audiokarmha forums.
Travis
Travis