Ohh I been through this. I bought a used crate out of a wrecked 85. The crate was installed by the local chevy dealer. Well the crate is a 94 casting and it had matching 94 timing tab on the chain cover.
So I drop this motor in and try to time it to the marker. Come to find out they put the 85 ballancer on it after several hours of cussing!
Looked at motor I just pulled out of truck and noticed timing mark was different location is how I figured out what they did. Used a bolt on the back of the water pump as a timing reerence from then on LOL.