Fuel lines

Then I can plug the vent tube at the gas tank and get rid of the line going back to where the canister used to be?

Sure, but keep in mind, the way I am describing to vent the cap is a 24/7 vent, it's not like a vented cap with a valve that builds pressure and vacuum and then vents. It will be vented all the time. I don't know why you would want to do away with that vent line though. I would rather use it for a liquid fuel return.