well the 1600 motor i have is been resently bored out and recondished and blue printed and is in a 1300 ute i have and the j13 is what was out of it and thought i would put that in the 1200 and i am now thinking of puting the 1600 in the 1200 ('73 sedan)
so puting it in would not make alot of difference because of its weight and its in abillity to rev as hard would a motor out of a 1600 be beter not sure what they are but i have one that came from a 1600 panel van
yeh ever thing from the dealers have genuine nissan parts or datsun there not some after market quick fix like the nos 1ns id got genuines over nos ones any day
just wondering weather there are any andvatages in puting a j13 in a 1200 i have no idea on what the torque or power of the j13 is but its out of a '67 1300 ute