Great story and progress! You're lucky that your folks drove, IMO, the best looking GTO ever made. In 1979 my folk's family car was a Datsun F-10, ha ha!
RE: your questions....
1- Gas tank. x2 on the black. It'll help hide it...
2- steering. I'd look into either sending that out for rebuilding with a faster ratio- or replace it (new if the budget allows) or if used- then look for a later model box like out of a 90's caprice cop car, etc. There are some articles online that will tell you the specifics of what can be swapped. Car Craft also wrote something on this a couple of years back. With all the suspension upgrades you're doing it'll be worth it to have a faster steering ratio. You'll be happy you spent the time to do this when the car is apart.
http://www.carcraft.com/techarticles...g_box_upgrade/