I had a special jig that I used to brace heavy bows, nothing more than a 2X8 with several 3/4" holes drilled down it's width and a support for the handle. Even with that it was a nightmare to brace it for the first time.
As far as dimensions go I didn't really keep track of the information but if I remember right it had 1 3/4" wide limbs and the length would have been in the 67" range
The backing was sugar maple and I found that maple is a more reliable backing than hickory and it was quarter sawn, or edge grain. I had access to high quality sugar maple from land I owned.
I'll try and upload picture to the site, I'll have to crop and reduce their quality to do that.