New to this forum and have a few questions

[c10chevy69]

Hello everyone. I just bought a 69 c10 lwb this weekend. It is a 350 4bb with an auto trans, ps, manual brakes, usual rust couple of holes in the floor under your feet. I do not have an owners manual with this truck so I wanted to find out a few things. How big is the fuel tank? It also has only two seat belts and I would like to add one in the middle any suggestions? Lastly what do I need to add power brakes to this truck? Any help would be greatly appreciated. Thanks.