Help for a rear end setup

Still digging at what I actually have here 5x4 small bolt pattern and made a thread about going BBP. I want to go dr diff rear disc brake and spring offset with axles so I can try to get a 15 with a 275. Rear is a little wet and really this hole car has to be gone through. It seems like a solid car so I don't wanna hack anything off it and really want a street strip car. I wanted to start with brakes and get the rear end right for new wheels and tires in the future.

Also looks like the traction bars would have to go? What are my best options here. And do the #s on the side of the rear mean anything? Sorry for the dumb questions.

20200523_172701.jpg

20200523_172221.jpg

20200523_171330.jpg