Sounds like you understand what j cAT's saying...at least thats how I read it and what I would do. Rigid copper pipe would be a good choice. Use the largest bit that fits inside the correct size tubing. Those are hardened bolts. Get a couple reverse drill bits as your gonna wear out some and alot of cutting oil. Keep that drill bit wet,cool and run it slow. Plug everything with rags, clean often and take your time. Good luck.