Fixing up a vintage Gitane and just tried putting new brake levers on the handlebars. I realized that the opening where the cable is supposed to come out of each lever doesn't match up with the hole in the handlebars. Is this going to be a major problem to find levers that will fit this particular handlebar? Should I just replace the handlebar? Any help would be appreciated!
It is EXTREMELY rare for anyone to route cables inside handle bars. Almost all cable housings are tacked (with bits of electrical tape or similar) along the handle bars, then covered with bar tape. The cable exit points on modern levers are positioned so that the cables are minimally intrusive under the wrap (bar tape).
If the bars are comfortable for you, run the cables on the outside. If the bars are not comfortable, replace. Make sure the bars are near the correct width for you, for best comfort and performance. To narrow, and your breathing suffers; too wide results your arms, shoulders and elbows hurting and more aerodynamic drag.
Nigel