If you need a boring bar for the outer tube of a can, start with tubing and machine the internals from each end. Quiet parts typically don't need tight tolerances on the inside. The fact that all the fancy stuff that people machine on CNC and sell for $2500 each has surely got people thinking that a device needs to look like that to work. Nothing could be further from the truth. Knowing a lot about devices is one thing, but knowing a lot about noise is enough to see that it's all smoke and mirrors, there's no need for anything more than simplicity. No stress!
I have run long bores with an underweight boring bar many times out of necessity. Boring with a wet noodle is still feasible if you do two things- one, make finishing passes from head to tail. Especially when threading. Two, make many spring passes. The reason you cut from inside to out is once you set the preload on your tool (skinny tool is flexing already), it will hold that point pretty well. If you go outside in, you get much more of a bellmouth shape. Then take a spring pass or four.
If you find a good deal on one, get a carbide boring bar. There is no comparison, they're a completely different animal than steel. If you are working against a blind bottom, the ones that have the inserts that cut edgewise are nice.