Mongo, now that is my kinda horn. I really like the base and throat, very good idea. The spirals, well, all I can tell you is go slow. I hand filed mine but I'm not sure you are gonna be able to do that on yours.I did decide that if I make another one with spirals I think I will make a small scrapper to fit the radius and scrapp them to their finial finished size
I think it is gonna be a great looking horn when you get done and I am looking forward to the finished pictures