My suggested first step would be to acquire all the necessary documentation you are going to need to understand the car and hopefully put it back together. Suggest:

Full Pontiac Historical Services factory docs to know what you have.

Full 1968 Pontiac Factory Service manuals to know how to fix things.

Whichever Factory Assembly Manual is best for '68. Don't know it the Firebird one is available or not. I do know that the best us "67 folks can do is the '67 Camaro Assembly Manual and the '69 Firebird one.

Finally, I believe there is now a First Gen Firebird Restoration book out there. I never picked it up and got limited use out of the 1st Gen Camaro book. It helped mostly with taking things apart which is not an area it sounds like you need help with.