shift lights are universal, you can tap your tacho signal from either the ECU (EFi) or negative ignition terminal (distributor). Of course the ECU is normally cleaner.
I'm running on a carb myself and if you can run a tacho, you can run this.
Tried to search for threads with regards to the Skyline 250GT but could not find any. Am looking to buy this car but need more info on it. Appreciate if any of you guys can share any info related to this...