Oh my goodness, I can't believe I, Mr. Technoklutz, am going to make a suggestion about a water-cooled conversion ... but here goes.
Make sure regardless of whatever method you choose and whatever material is being used you employ mandrel bends. An inch and a half or an inch and three-quarters won't mean squat if you have bends pinching off at seven-eighths in places.
And now, back to the experts.
