[tsuter]

Yes, You can just cut the tube after the check valve and weld it closed. Then when you have better access unscrew the tubing assembly from the injectors first. That requires a 14mm backup wrench on the air injector to keep it from turning. Carbon build up on those air injector threads make them difficult to remove from the heads. I would spray with wd-40 and allow to penetrate as breaking the tubes off at the threads would not be cool as you have surmised. They absolutely will brake off at the threads if forced.