Wiring Harness Removal

[Bonehead]

Started small restore on 76, four days later I have the body off and the chasis outside the shop,Whats the best way to remove the wiring harness from the fire wall the gromets are stiff and brittle; Also I have a reman 302,holley 4bbl that was installed before I got the truck , Question the vacuumm hose leading from the port on the engine to both fuel tanks was not reinstalled ,just left hanging ! does this need to be reinstalled or can i do away with the lines to the tanks and cap off the ports?