I'd like to know more info as well, but all I can say is the timing tab is at the wrong place.
The fieros had the tab on the left side (looking at the front of the timing cover).
My opinion is to find an original V6 engine from a 87-88 fiero and grab it.
As we know, the 88 had many small changes. (engine parts internal and external)
88 GT, Loaded, 5-speed.
88 GT, 5-speed. Beechwood interior, All original.