Did the PO chitcan the original filler tube/vent tube? The 76 has a big azz hose for the filler and a smaller hose that fits into a 'fitting' that is pressed into that big azz hose. But you're in luck. For some reason, the aftermarket makes a filler hose for the 76 Jeep (but not the 77-something I recently was told). And the small fitting? Junk yard.
Better to convert over to the 78-86 CJ style filler assemby:
Of course...You're gonna have to 'Hack Fab' it in with the later model tank.
As far as fuel lines go, you can order pre bent lines from a variety of sources...However, once you start 'upgrading' don't expect things to 'bolt in'.