Have you looked at glampyre's boobholder? http://glampyreknits.tripod.com/glam...otos/id62.html
Lots of people have made the fronts wider so they'd meet where you'd put in a zipper. Just co extra sts so that each front has half as many as the back sts, but don't increase along the front edge, just at the raglan sleeve shaping. And you can make the sleeves whatever length you want.