SIX2GO, Joe Lubrandt will have you together with the chip burning. However............
FWIW I would switch to the 86/87 ECM as soon as you can. If you can do it before getting the chip, it will save you on wasting $ on a chip that you wont be able to use when you finally do change over.
After hooking up my TLink on a fellow '84 owners stock car a couple weeks ago and seeing how pitiful the lack of info given was..... its a no brainer that any 84/85 I put together in the future will get the swap right away. I did mine before I even had the car all the way together, so I never saw first hand how bad the data (or lack of) was with a scantool.
The swap is just too easy and CHEAP, and you can do it yourself. I wound up changing the guy's ECM a couple days later in about 30 minutes max. ECM = $10 from the junkyard, MAT sensor & plug (so check engine light doesnt come on) = FREE, wire = had plenty already laying around. The following week the guy got a Scanmaster (couldnt use with the old ECM) and rapidly is on his way tuning and improving the car much easier. There are instructions over at gnttype.org for this swap. However, the job is much easier than it may at first seem in the instructions. Read through it, you really dont have to pick through wiring harnesses, etc. to accomplish what you need. Just need the ECM part #1227148 (Ive found several in several different front wheel drive vehicles), the MAT and its plug, and cut/take a ECM plug from the car in the junkyard so you can use one of its pins for the installation (mise well just take the plugs with the ECM you get; cut back far enough so you have a bit of wire for an easy splice).
Use a length of wire to extend the MAT plug wires from the air cleaner to your current ECM. One wire from the MAT sensor splices with ground wire D-12 (black wire)pin location at your ECM. The other MAT wire (this is where you use a pin from the plug that you got from the junkyard) insert into pin C-11 (tan). Plug the 87 ECM in. Use the cal-pak (will read either 16036503 or 16036504 on it) from your 84 ECM and a 87 chip, and your done. EASY. [Solder your connections].
Just my 2cents
