Hey Derek,
That sounds like quite a stave. Was it split from a larger log or was it a sapling or branch?
As far as tillering a stave with that much reflex, you may find as you begin to tiller that you lose it quickly, or that it may be nearly impossible to work with. If it were me, I would tiller it to brace height at full length to get the wood used to bending. Once it's braced you could leave it strung for a day to cook a little of that reflex out. Once you've tillered to full draw and the bow is used to bending and shows signs of being willing to bend further, you could shorten it and retiller.
Basically, you're in for a challenge making an ELB out of a stave with that much reflex. I know Marc did it, but that was an impressive feat.
1 1/2" wide at the grip and tapered to 1/2" nocks is about what you're looking for.
J. D.