87 to 90 engines

[grkguy]

i have a 87 500 that has busted bottom cases i bought 2 new to me cases for a 90 model will all of the internal parts work in the 90 i know that the counter ballencer seal is diff from the to years just need to know if it will be ok or do i need to get 87 cases when i got the 90's they were empty no gears but i am running a brand new jug from suzuki on it the 87 model with a 7 bolt jug just some help on this would be great thanks for your time