Never made an ELB from ash, but my formula for decent to good white woods (elm, ash, mulberry, hard maple) generally runs about the same.
Somewhere between nose-picker height and as tall as you. 1-3/4" wide limbs, minimum. 1-3/4 " wide limbs, 2-1/4" if you can get it. You can always narrow a bow that is taking very little set at about 24" draw while tillering. Short handle, short to medium fades, and anything from American flatbow to Meare Heath front profile and tiller. Molly if the limbs can be wide in close to the handle.
If the board is cleanly flat sawn chasing a ring is not a bad idea, but if the rings run straight, you may not have to. If you use a board stave, fudge toward more width.