Wiring Harness Madness

I am converting this '84 LX over to '88 5.0 spec. It originally came with a CFI 3.8L V-6 and a C5. I'll be transplanting a V-8 from an '88 Mark VII LSC and an AOD from an '89 Town Car. My question involves switching over to an electrical system that will support the EFI. Since I'll be going with the stock heads & cam, the Speed Density system will be fine. I got a free dashboard with wiring harness from a guy who said it came out of a GT; however I have no way of knowing for sure. Even if this harness will work; the sheetmetal of these two engine compartments seems different, particularly the firewall. This harness utilizes a large round hole to pass through the firewall in the '87-'93 which the '84 seems to lack. How can I overcome this obstacle, and what am I to do about the engine bay layout?

gork1rogues said:

Create the hole.

Click to expand...

Works for me!

I actually just found somebody who did almost this exact same conversion 4 years ago. He is in contact with me now so looks like this is going to be my best resource; although I am still open to suggestions...

So it appears there are two holes-one underneath the power brake booster (for the steering) and one under the heater core outlets; this one looks like a drain hole for the A/C condenser. Since I won't be using A/C anyway; guess that's the one I'll be using. Could be made larger if necessary. I wonder if this is the factory location on later cars? Guess I'll need to do a little research in the junkyard with the digital camera...