I have an Ontario Hell’s Belle, ordered when they were still being made. The original sheath is not suitable for carry, being far too tight. I am not so sure it can be loosened without ruining it, and have been considering options, including ordering a leather Rowe sheath, or Kydex from Mike Sastre. You are correct; the coffin handle does work very well.
A maker named Covington has indicated that he has Bill Bagwell’s blessing to use the secret Bagwell heat treat. He used to be local, near Bagwell in SE Texas, but went quiet for a while, and then re-emerged in a new area, and makes the Hell’s Belle. He lists on evil-bay, from time to time. Whether he takes orders for a Bowie sized to fit the user, I cannot say. I hope to learn more.
I am tracking a pre-owned Covington Bowie, en route through the USPS, from a collector in NJ. This Covington blade is not anything like an HB, being much shorter, about 7” in blade length, and with a different handle contour.
Regarding Bowie sizing, Bill Bagwell wanted to know a specific dimension of a user’s physical size before making a custom Bowie. I believe my copy of his book was turned to mush by Harvey, but a new copy is en route. Another method I have found, on-line, uses the user’s measurement from inside the elbow joint, to the inside of the bent middle finger, a measurement that also tends to match the dimension along the inside of one’s thigh, the sizing of the sword used by the Biblical Ehud.