[El Jay]

Strange. You'd think with all the after market, rear tank kits out there that somebody would offer a fuel line set up.
I think I'd do like PanelDeland said & go with "burb" fuel line, if the tank is a "burb" knock off.
If you have a short bed, maybe you could cut a section out of the line & put in a "hard" coupler, so as to reduce the amount of rubber connections in the system.
C20_Paul's idea to put a filter in @ the frame isn't a bad idea either, IMHO. When I installed a pair of saddle tanks on my '76 Jimmy, I did the same thing. All 3 tanks ran through that 1 filter before they fed the fuel pump.


As for the mounting hardware, I'm going to go out on a limb & guess that it's grade 5, or better. If you decide to go with Nyloc nuts, make sure they too are grade 5, or better. I don't honestly know how Nyloc nuts are rated.
I do know it would be a crying shame to have a nut failure (that didn't come out quite right!) on a fuel tank mounting.

I'm not qualified to comment on the brake line.

You are now the proud possessor of my .02.