Yes, you can just soak your bushings in a a bottle of acetone, that will get the CA off. But the real solution to matching the diameter of the tube to the parts is to measure the parts with a caliper, and then turn the wood to match measured with the same caliper. Don't matter what method of turning you use, bushings or between centers or whatever. I usually measure the part in question and lock my calipers on that measurement, then start turning the blank, and measure every so often once I get close. When I get right down to the point where the calipers will ALMOST slide down over the blank as close to the end as I can see to get it, I then switch to sandpaper and take it down till the calipers will just slip over the wood at the very end, and slide back up the curve just enough to see the wood behind them. That gives me just enough room to build up a good CA finish. But remember sanding is removing wood and making the blank smaller, even with fine grits, so don't get it just undersize, and THEN start working your way up through the grits, or you will have a lot of coats of ca to apply to get it back up to size. It's a "feel for it" kind of thing to guess just how much undersize to sand, and depends on how you like to apply your ca finish, and other things. But it's worth it the first time you can close your eyes and run your fingers down a pen, and not feel where the wood ends and the metal starts.
I recommend getting a dead center for your lathe to use with your live center for applying finish, even if you turn on a mandrel with bushings. You can just put the bare blank on between centers and apply the ca without getting it on your bushings, and without chipping it trying to get the bushings off. But beware, if your bushings are not perfect, or your mandrel is bent your blank will be out of round, and you will tend to sand through one side of the ca, and that's the beginning of the slippery slope to turning between centers all the time
