When you first told me about the Omega I was all for you grabbing that and building that car. Now that I have thought about it a little more and found out about that '84 GT, in my humble opinion, I think you should stick with the Mustang.
Since the Omega hasn't been hardly driven for the past decade and a half much of the suspension will be shot. The bushings will be hardened and in very bad shape, and these are a PITA to replace, trust me. I've done it on two different 33 year old Mustangs, one of which sat for most of it's life.
You will spend too much time on the Omega turning it into a safe, driveable car on the street, and not enough time on customizing and modding it and making it track worthy in my opinion.
I also agree that sooner or later you will regret on jumping on that deal and not having your beloved 5.0!
Either way I hope it all works out great for you, man.
