eBay is your friend there. Or it may be found here if you post the particulars. I picked up mine from a forum member.
Some may be interchangeable but not all due to exhaust, engine, suspension, etc. considerations.
2016 Yamaha FJR1300ES
1982 GPz750 R1
1974 Kawasaki H1
1976 Kawasaki KZ400
1979 Yamaha XS650 cafe'
2001 Yamaha YZ426
1981 Honda XR200 stroked in an '89 CR125 chassis
1967 Triumph GT6
"If you didn't build it, it's not really yours"
eBay is your best bet, and yes, the center stand is model dependent. You need to know exactly which year and model bike you have, rather than just a 1982 KZ750. In 1982 Kawasaki made the KZ750-E3; KZ750-H3 LTD; KZ750-M1 CSR Twin; KZ750-N1 Spectre; and KZ750-R1 GPz models. They do not all use the same center stand so knowing the model really matters before buying the part. Ed