I have a 1972, 1200 datsun with a 14A engine that has been fitted recently. The ratios in the 1200 box seem to be a bit high for the 1400 motor is there a simple solution to this problem?

If the ratio's in the 1200 box seem high for the A14, then they must have been mountainous for the original 1200. I thjink that with the extra torque & power of the A14, you probably mean that the ratio's seem low.

There are a number if ways to address this problem, & they include, in no particular order,
60 series 5 speed [overdrive] box.
Larger diameter rear wheels/ tyres
H150 diff in 3.7 to 1 ratio with spacer in original H145 axle housing
Substitute H165 ute rear axle assembly & use 3.7 to 1 diff from series 1 & 2 Bluebird sedan that originally had a four speed box.

Any one of these will help, or any combination will help even more.

thanks will give it a try