You can't plug it. You have to loop it so the displaced air (formerly fluid) has someplace to go when the wheels are turned. When you remove them, take them to the auto parts store and see if they have any metric brake line or barb fittings with the same thread. But your best bet would be a hydraulic hose repair shop. I don't think it would cost $20 for them to make you a nice one. Or to replace yours if you cut them and decided to put the power steering back on.
Remember, reducing the caster in your alignment down to 4 or 4.5 degrees can reduce steering effort if you find it to be slightly higher than desirable. Mine is at 4.5 and it is great. It is an excellent mod.
Be sure to get all of the fluid out that you can. With the front end on jackstands, the lines off and the steering unlocked, grab one of the wheels and slam it left-right-left-right as quickly as you can. Most of it will spurt out and what little is left will remain inside to lubricate the parts.