just wondering what you do with the fuel return lines when you're going carbureted on a GTS. I have the return line as well as the hard lines from the canister sitting next to the firewall. Should I plug them up?

yes plug them or you might get pressure pushing out fuel through them. remove the charcoal canister and plug the return line that normally went to your fpr.

should the lines be fully capped? Capping them won't build pressure in the tank?

you should have a gas cap that releases negative pressure. oem should be fine.

Capping mine built a lot of vacuum pressure in the tank. I never got around to making a rollover vent before I sold the car.

cap it