There are handlbars from the days of yore that are appropriate widths for more modern positioning - you just have to hunt for 'em. The standard in the 70's and even in the 80's was 38-40. The theory was that the narrower profile offered a smaller profile and less wind resistance, and less chance of hooking your competitors in the bunch. I just always felt amazingly compressed. Modolo introduced the modern 8 bend ergo bars in the middle 80's. You can still find this pattern in new bars today (or an original). Those would work with you stem. If its more of a Maes bend (traditional, with 4 bends and flat tops) a Cinelli Top Ergo 66 from the 90's looks spot on for older bikes, and doesn't use the cinelli-specific 26.4 clamping area. Or watch eBay, find a 3t vintage bar in an appropriate width, and expect to duke it out. You aren't the only one who wants a wider vintage bar...