When you throw a sr20det in to a USD 240sx (at least the 91 model I did it on) we had to replace the cluster b/c the ka24 was a sohc, and the sr20det is a dohc. Also I have been doing research while restoring my 84 300zx which has an electronic display needs a diffrent clust cause I am putting a rb26dett in it and the cluster shits its self if you plug it in, even though in japan they had a model of the z31 with a rb20det in it called a 300zr. So, I was drawing this from my history with nissans. I know that for instants when I helped my father replace his 70 ford galaxy engine with a 428, we did not need to replace the cluster, so yes, I have some expirience on this and I have hear whether you have to or not.
Also I think, I'm not sure, but the tech goes higher number wise then the civic, and I thought the speedometer goes to 140, where as my civic goes to 125ish. I don't want to be shifting too early or too late, and the last thing I need is get pulled for speeding again and the cop starts asking me if my car is street legal. Idiots I went to high school with that thought they where racers desided to do stuff that isn't legal, so cops where I live which look over your car if you even look like a ricer or a tuner.