wish i knew the length of the sunny control arms, I know that the arms from most old RWD datsuns seem to be interchangeable, difference being camber. i think the lower ball joints all use the same bolt hole spacing, if not, they seem to all use the same strut tube diameter, so use whatever ball joint fits the control arm.

really old 1000's might be different, but 210's/510's/810's/and such seem to be reasonably interchangeable.