I have a set of yew billets that I've been saving for a special occasion.  Well, I found out today that I drew a bighorn ewe tag here in Colorado, and thought this would be a good time to employ these billets.   The billets are very straight, however, the ring count is a little low compared to what I've read about.  They only have about 22 rings/inch and has about 1/2" of sapwood.  I would like to make a 66" bow, similar to the Chet Stevenson bow that was on the cover of TBM some years ago.  
 Never having worked yew before, I am a little cautious to start whittling wood.  First, should I work the sapwood down to maybe a 1/4" or so?  If so, do you try to stay within one ring, or just make sure the back is flat and even? (I had heard a little ring violation in sapwood was not a big deal).   I would like to make the bow 66", and 1 1/4" wide to midlimb, with a deep core and slightly rounded belly.   Is this a reasonable expectation, or should I stick to more of a flatbow style?  
  I know there are some yew gurus on this site, please feel free to chime in with your advice.

