you have no idea what youre talking about. i know one of VERY FEW people that have gotten almost everything to work from an S15 cluster into an S14, and if i remember right, it was the speedo that didnt work due to a few factors. regardless, it requires extensive wiring and circuitry knowledge, and even if u are a pro, its a long trial and error process. unless you just want it there for looks, go ahead, but its not worth the headache if you ask me. kouki clusters into zenki's is much simpler, yet still complicated. re-wiring is needed. there might be a writeup on that on Zilvia, so search harder, i know there are some instructions on there. i believe theres a write up for youre speedo to read kph to mph. honestly tho, my car reads up to 180kph, its the stock white background cluster and im happy with it. the nismo optional one reads higher, but has a black surround. in the end, its a ridiculous amount of wiring. what i want is the clusters they get in Poland. i had an old pic of em on my old mac, not gonna look it up now, shit is sick. the increments are more european while still retaining the japanese design to the cluster itself.
good luck.