Just had a measure of my ELB 50# boo backed Yew flight bow, ()mind it's only 66" long.
The Yew is a whisker over 5/8" just above the grip. Ipe is stiffer, but your bow will be longer.
If you prepare the boo with it thicker near the centre so it tapers to the tip, that will give you some extra thickness, and you may be ok. You'll prob need to glue an extra 3/16 - 1/4" slat to build up the grip area a tad.
Del