shouldn't really be a question of whom is in the right, more a question of common sense.
aircraft 1 is already in the circuit, and part of a standard overhead join is to suss out the circuit traffic/direction and fit in accordingly. if as a result of a joining downwind a little too tight, aircraft 2 should accept this and widen out to give aircraft 1 room.
also if aircraft 1 has turned base, probably descended through the circuit height and if i recall, a lower aircraft has priority.
the "on the right in the right" rule really goes out the window in circuits.
anyhoo, i would say aircraft 2 should yeild to aircraft 1, but more for airmanship rather than any hard and fast rules.