Several things-

There are PLENTY of non-turbo GLH's out there.

If swapping to make legal, you have several issues-

non-turbos use a different hub setup than turbos
non-turbo rear drums are 20mm smaller

You need a non-turbo engine. The H.O. motors were decked slightly and of course had the Shelby cam. Wiring was completely different in the engine bay, and of course the computer is way different.

Trans is shorter final drive. Yes, I know they're free, but trust me, you WANT the 3.87 F/D and not the 3.56.

If you do decide to build one, there are a few people around here who know a little about them. That being said, I personally don't think the car will be a front-runner in ITA, even at the limit of prep and development. It's at least got a better chance than the Shelby Charger. You have weight issues, ignition system limitations, and an antiquated suspension and braking system to deal with. Any one of those things is not a big deal, but all together, it makes an uphill battle.