Check with Doug @ Custom buggy parts, He can build a beam to your specs.
Best way to get ahold of Doug is to call Hawkeye Buggies.
Hey Billy, Ive got these fiberglass lay back seats for the wife's rail, the seat covers are well cr@ppy at best. I was wondering if bring one of the seats to the classic could you take it and work your magic on some new covers that would be a little more suitable for a girl.