well i’m pretty sure that the 14 hinges line up in the back with the s13 holes, but as for fenders the s14 are shorter in lengh and taller in height. you’d need to fab your own, but it might work
they will fit somewhat! Headlight brackets are easy to make. You just move over the Silvia ones a inch or so and the rest of the lights blot to the fender! The fenders are wider and I am 90% sure the hood can just bolt to the factory S13 hinges! Also you would have to space out the hood clamp about 3/4 of an inch!
the first hatch i ever saw with the S14 kouki front end was at Autodreams shop. they were installing an RB at the time and Marvin let me see the beast.