1980 KZ250 rear wheel does not seem to fit in swing arm

I inherited a 1980 KZ250 that has been in my in-law's family from the day it was bought off the lot. It has been passed around to different family members who have ridden it over the years. When I received it, it hadn't been ridden in perhaps 10 or 11 years. I found that the rear wheel assembly was missing the sprocket bearing and the sprocket side spacer. I also later found, after buying the service manual, that the break side spacer isn't even the correct one. So I went to eBay, I found a set of axel/spacer/tensioner from another 250 of the same year. I also managed to find a used factory sprocket with the bearing and bearing seal inside of it. I communicated with both vendors and they insisted they both retrieved the parts directly off of a kz250 1980. All of the parts seem to match what is in the diagram in the service manual. When I reassemble the full rear wheel assembly with my new parts the end-to-end distance between the two spacers is about 0.25 -0 .5 " too long. I can not get it to fit into the swing arm although it seems very close. I did manage to get it in by having a friend apply some serious leverage on the swing arm to give me enough space to squeeze it in there. And after inserting it everything seems fine and the wheel tracks. I'm just curious if it is normal for it to be that difficult to inset a wheel into a swing arm or if its something else. I thought maybe someone at some point may have tightened down on the axel nut so far when the spacers weren't in that it bent the swing arm ends in but nothing seems to be asymmetrical about the two sides. Another possibility is that different models of the KZ250 had slightly different rear wheel sizes. Does anyone have any input on this?

is your 250 a single or a twin, as I think both were offered in 1980. I do not know what if any differences there are between swing arm or rear wheel between the 2.

It is a single, I did not know they also made twins the same year,Ii'll research that. Thanks for the input

Here is some info on the twin.

bikez.com/motorcycles/kawasaki_z_250_a_1980.php
z250.co.uk/z250b.html