Most all hardware stores stock 3/16" copper tubing (52Carl knows how I know this). It is not that un-common a size on the hardware side...might be in the automotive industry though. Weatherhead #6100X3 is the crimp nut, Weatherhead #202X5 is the bushing that screws into the block that the crimp nut fits. Napa sells both.
I personally used copper tubing on my 216, (if I remember correctly, that was HRL's advice to me....so listen to yourself). The copper allows for some flexing and bending, and you ARE going to need to do some flexing and bending, as you well know. Stainless would be my only other idea of what to use, but finding it would be fun, and it ain't gonna be agreeable like copper is. For me, anything that could rust or corrode, (like the steel brake lines), is out.
Several feet of copper and a few of those fittings is way cheaper than one of those 'kits'.
