old fuel lines and brake lines -Replacement Where and How? Tech tips please!

Buy a 25' roll of 3/16" steel tube, a pack of fittings, get a flare tool, and go to work. On your F-body all the tube fittings are gonna be 3/8" except where it goes into the master.

Even the steel stuff is easy to bend and easy to flare.

Unions suck. Forget the pre-flared, pre-length stuff. Unions are just one more place to leak. Running full length from one end to the other minimizes your chances.

Fuel line? There's a place for rubber line. Replacing the entire pipe system ain't it. Use rubber just like the factory did, flex connection points and put in metal. Get a roll of 5/16" and get it done.

By the way, in my opinion Ni-cop isn't worth the money you spend on it. I've seen it corrode and leak quicker than steel. Too soft in my opinion and takes finesse to flare it without overflaring.