The oil pan is not a simple bolt on and we're done deal.
There are some things that need to be lined up properly between the crankcase and the oil pan upon installation.
Under: Crankcase fiche:
https://www.partzilla.com/catalog/kawasaki/motorcycle/2000/concours-zg1000-a15/crankcase32033 32033-1201 PIPE,MAIN GALLARY - including Orings
32033A 32033-1202 PIPE - including Orings
92075 92075-1785 DAMPER,PIPE
92190 92190-1075 TUBE
Under: Oil Pump/Oil Filter fiche:
https://www.partzilla.com/catalog/kawasaki/motorcycle/2000/concours-zg1000-a15/oil-pump-oil-filter49065 49065-1066 (Sump) FILTER-OIL - The top of this clips onto one of the oil pipes listed in the first section
92043B 92043-1213 PIN,18X20X12 (the one on the bottom of the oil pump)
I'm recalling the involved parts from memory and looking at the fiche's.
There MAY also be an external oil line that connects to the Oil pan from the crankcase too - but I don't recall exactly right now. Check to be sure.
Study where these parts are on dis-assembly and make sure they are in place when the new oil pan goes on.