My father-in-law lost his right leg in a motorcycle accident back in the early '60s. He still rides his '53 Triumph today. In fact, we're going for a ride tomorrow night.
Anyhow, back to your question. I don't know of a kit, but what he did was add a shifter linkage that runs from the right side to the left side. (Remember the old Triumphs brakes and shifters were reversed) He brakes and shifts with the same foot. I would think you could do the same thing for the brake.
By the way. Congratulations on getting back in the saddle.
Kem
father-in-laws bike