Welcome!
As has already been indicated, your moto has mixed parts. The fairing is from a K100RS. The round headlight might be from a K75C or it might be custom. The handlebar has been mounted on a riser instead of using the stock mounts. The seat is a low-seat model. The side cases are late models so they have the largest capacity of all cases that were offered. The fuel tank has custom paint striping.
You should probably order engine, brake, and electrical parts based on the 1988 date. Take the screws off the fuel tank cover assembly, remove it, empty the fuel tank and inspect the tank's interior for sludge.
Thanks for posting photos. Take one of the handlebar setup from behind it with good lighting so we can see what type of dash pad it has.