There are enough Cinelli stems for sale that you could probably buy one with good hardware, exchange your stuff for the nice bolts, then resell the stem without taking much of a beating. (Making full disclosure, of course.) The chrome bolts will do fine if you keep them clean & dry- wax helps, and a little WD40 will dry them out if they do get wet. Titanium can create a few problems (look up galling) and a 120+ mm stainless metric allen head bolt isn't something even specialty hardware places are likely to have. You can try Metric & Multistandard Components Co. at 800-431-2792. Good luck!