Can't help you with non US frame numbers but...
I have several carb numbers that should help you narrow down the year range:
http://www.oem-cycle.com/KAWASAKIKX500BIKEID.shtmlAlso, compare your fork info to that of the chart (Scroll way to the right).
You may be able to further narrow down the year.
If you are wondering why salvage companies are little help in identifying bikes it's because they are not authorized factory dealers and have no access to factory information.
As a salvage company the only way you can get that information is to pay very close attention and record everything which takes a lot of additional time per bike and takes years to develop.
When I started to develop my information I did it because I was tired of selling the wrong parts and having to pay for return shipping and I didn't want to have upset customers.
Once I had a large amount of data recorded I decided to make it available.
Very few salvage companies have the time, money, or patience to put it all together.
Because the engine ID's are not listed after 1989 here is a list of numbers based on bikes we have parted out as well as other member's numbers.
1983 is KX500AE000001 - KX500AE001500
1984 is KX500AE001501 - KX500AE002400
1985 is KX500BE000001 - KX500BE001800
1986 is KX500BE001801 - KX500BE004100
1987 is KX500BE004101 - KX500BE006600
1988 is KX500BE006601 - KX500BE008500
1989 is KX500BE008501 - KX500BE010700
1990 is KX500BE010701 - KX500BE013000
1991 is KX500BE013001 - KX500BE0134xx
1992 is KX500BE0148xx
1993 is KX500BE0164xx
1994 is KX500BE0175xx - I think this one is wrong...
1995 is KX500BE0172xx - KX500BE0180xx
1998 is kx500BE0195xx - kx500BE0197xx
2000 is KX500BE0219xx
2001 is KX500BE0223xx