Anyone making "wrought iron" gates would do this in minutes if you can't manage it yourself.
I've just sent 2 off to the paint shop.......An original off a single and a replica for a twin. I would say the originals were probably done in some kind of rollers to get that shape. It is also worth noting that the pipe is supported by another band style clamp immediately bellow the rear of the kick start cover on the gearbox. This clamp arrangement is also attached to this same muffler bracket via a 5/16" diameter hole just behind the two 1/2" holes that mount the bracket to the lower engine/gearbox plates. I'm only going off pictures I've seen of these in Bickerstaff's "Original Vincent" that clearly shows the band clamp. Without this the exhaust system will shake sideways quite badly, and this will loosen the joint at the exhaust stub. All of this is important as the clearance for the kickstart levers is affected by this.
Blacksmiths can still be found in country areas where people have horses. They might not be called 'blacksmiths' anymore but there is normally someone around who can make bits for a tractor at short notice etc. I can think of two within about ten miles of me who do general machining, welding etc and this is south east England, one of the most urbanised parts of the UK.