Anyway, I've tried to follow the forum's guidelines with pictures, so here goes.
Something like a Billiard:






I made this stem (unlike the one below which is a pre-cast vulcanite one). Stems are hard.
And almost a Lovat






So this is where I had to amputate the original stem and replace it with something else. I went with a bit of old Lignum Vitae I had lying around, which is possibly not the best choice due to it's high oil content.. but I'm hoping it's not a catastrophically bad idea, as I've done it now. Hoping that because it's not in the actual chamber it won't be an issue, and I could always sleeve the inside of the airway along the length of it with a bit of stainless tube..