Regarding the Tartans on your list, I would not want to cross an ocean on the 28 or 30, they are more light racers than cruisers(fin keels,spade rudders, lighter displacement). The T34 however would be an excellent choice for the money if you can find one in decent condition. This boat is now 30+ years old and will need some attention if it hasn't been maintained. The T34 will give you the performance and stability that has made her a classic. How many will be living aboard? Just you? As with any small/midsize boat, layouts can get crowded if you get too many people trying to fit into one space.
Another option is a T-27 in good shape. These have cruised far and wide.