I'd have to check on my GT, but I've modified the engine bay for the V-6 install, there is a boot for the brake rod, some grommets for the wiring harness and hood release cable, but most of the grommets can be had at a local electrical supply house. The throttle linkage I don't know, that was removed entirely along with the sheet metal in that area, a couple of years ago. HTH.
The best way to install that seal is to drop the steering column from the instrument panel and structure, then disconnect the shaft at the steering rack. Pull the shaft back far enuff to slip the seal over the end of the shaft, then slide it up to the firewall and slip it over the flange. That's it.