I would highly suggest subframe connectors.
The years for the GTP are listed but you need the correct spacers and washers. SHONut no longer sells them. You also need to pull them from 2 different cars.
For the time and trouble to find them and the hardware, I think the Ingalls are worth it: SHO Source
I am not sure what you mean by milled for the h-brace. They are welded together.
Coilovers would be the next step: SHO Source
I'm for sure doing Subframe connectors, and I'm looking at getting an H brace and rear STB. I'd like to get the rear adjustable arms (either GTP or Ingalls).
I don't know what I meant about "milled", just had a brain fart
Coilovers are out of my price range at the moment but thanks for the ideas.