E30 M20 Swap Gauge Cluster Questions

[NVADER 54]

I have a a motronic 1.3 m20b25 that I'm putting into a 1990 316i. The car is pov spec and has the clock instead of a tacho.
I also have a mint cluster from an '86 320i which has a tacho. Haven't taken either apart so my knowledge in this area is all courtesy of the interwebz.

1. I'm guessing the 320i cluster is pre-coding plug technology and so won't work as is without some crazy custom wiring but would I be able to transfer the tacho from it into my 316i cluster without much hassle or are pfl/fl clusters completely different?

2. Will the 316 cluster work if I replace the coding plug with a 325i one?

3. If 2 is a yes, are the coding plugs specific to Motronic 1.3 or can they be from any 2.5?

Thanks in advance