Wel after further review of those links..
I have noticed this page.
http://www.ecanfix.com/users/mdhamilton/ecuwiring.html
So i think the only differance with the ecu would be pin 6 and 14.. Is this true? If so all that would be in order is to switch the pins in order to use the 90' ecu.. Of course with a detailed note explaining why I did this taped to the 90' ecu for future owners lol..
edit**
1. Deal with the ecu wiring first. The only difference between the 1990 and the 1991-94 ecu pin outs is pin 6 and 14. Just swap these two pins by cutting and soldering and heat shrinking. (or just pull out the pins)