late mk2 calipers have the handbrake mech on the back of the caliper
early mk2 have them on the side
they are straight swap on late mk2 calipers, no fiddling with handbrake cables
if you want mk3 calipers on an early mk2 then you need the later mk2 cables, and need a small bit of rerouting
and the usual word of advice, make sure you get late mk3 calipers, as early mk3 = late mk2 calipers