Look at northroad bars as well as pullbacks (cruiser bars). Make sure your current bar is 25.4mm where it clamps to the stem. If the rear wheel is that close to the seat tube you may find the bike tippy with cruiser-style pullbacks. It will want to pull wheelies if there is a grade or if you pedal hard.

You may need cables too, because the cable ends might not be compatible with any levers for a straight bar which you buy.