Gas Line

How important is it to replace the gas line...(the line from tank to filter) on a car that has sat and not run for maybe 20 - 30 plus years..? I know when the tank came out the gas smelled like maybe varnish ..? VERY strong smell.
I already have the new line, so most may say to just swap it, but I'm finding it's a major pain in the *** to remove the old one... and before I go to yanking, twisting, bitching and punching something, is it really necessary and worth it..?
If so, any good tips on removal and install..?? 72 Demon.
T.I.A..!