There's two types Jim. The suzuki type has two cables lead to the lever itself with the lever having a pivoted balance bar with the cables attached. The second type has a normal lever with one cable leading from it to an intermediate pivoted balance bar with two cable leading from it. I don't think it would too much engineering to fabricate this style.
Failing that, if you want to buy 'off the shelf' there are one or two Italian manufacturers of double sided front brakes that advertise in the Classic Race magazines. You probably find sites on the net as well. I'm sure they would sell the levers and perchs seperately.