Kits are available from The Rifle Shop.The type you place on the end of a stick. Something like from the 14th century.
I have shot everything from .735 patched round ball to hemp packed round ball to over powder cards and #7 shot and 9 count of 380 balls. I have loaded with 30-130 grains of 2F and it is all FUN - every time.That is sweet looking. I tried contacting the rifle shoppe by email then by phone but no response. I like how the Hakenbushe has the spike built in. Your finish is excellent. What is the load you are banging?
If you have access to a lathe it would be very easy to turn the barrels. Just need to make sure you use the right steel to make it safe.The stick is called a tiller. We used to have a member here, Freak Forge, who made some very affordable gonnes, but I believe life came along and pushed him in a new direction.
TRS also sells the match cord - it's cheap and a lot easier than making it yourself. It burns really slow too!As said before keep trying TRS. I have the steel .75 with the s lever. High quality and shoots great. Surprisingly accurate... While your waiting for you gonne order some 1/4 to 3/8 100% cotton or jute BRAIDED cord and potassium nitrate off amazon to make slow match and find a pen ash or oak 1 1/8 shaft and you will be ready when it arrives.