Quote:
Early head = Datsun 1200
Late block = A14.

This is the plan for me, I have my 1200 GX head all ready to go, except that I am using an A13 engine which is the same as a 1974 & later A12 engine, but with a bigger bore.
Think of it as an A14 with a shorter stroke & deck height.

The GX exhaust manifold is the factory competition department's recomended exhaust for cars used in Rally applications. These engines were bored to over 76mm & this made them only a few CC's short of 1300.
If it's the factory recomended item for a 1300 race engine, then it will be just fine on a 1400 cc street engine.