Howdy S.S,
I've made a few Red Oak Board Bows for hunting. And, I've just reread the TBB-1.
Your question was about a 2-1/2" wide and 62" long bow. I'd say it's a bit short - it could be done, but you'll get some stacking.
What is recommended in the TBB-1 is a length of 64" to 67", and a width of about 1-7/8". But, go ahead and try 66" by 1-3/4". Keep that width until about 13" from the tips where you begin your taper to 1/2". This is a stiff handle design. So, you'll have to glue on a riser, that's no real challenge. (If you decide to go this rout, I'll walk you through the glue-up if you want. A good glue line / surface can be obtained by following a good glue-up procedure. I've never had a riser pop off for me.)
The TBB-1 is a real good read, and there is a section on stiff handle design - check it out. Also, Jawge's web site is a very valuable, informative guide. It has a number of Build-Alongs.
Good luck,
Canoe