1981 to 1984 engine swap

I've got a 1984 kz550 with major oil leaks. I am having trouble finding rebuild kits and considering just swapping out the engine. I found a 1981 kz550 that looks to be in good shape but I'm wondering if anyone knows if it would be compatible or if there is a good resource for finding this out.
thanks

What models? KZ models are designated with "KZ550" then one letter, and one number.
An 84 KZ550F2 would be a second year, shaft drive, Ltd/Spectre model.
All of the chain drive motors will swap with each other, but some use slightly different mounting hardware, and some use different carbs and, therefore, different airboxes.

If the 84 is a shaft drive, then you will have a hard time swapping in an 81 engine as they are all chain drive.