I have made 3 pc take downs, longbows, recurves and a hybrid longbows. I have also designed two different bows. One a recurve and the other a hybrid long bow. For the two that I designed I pulled the parts of different bows that I liked and put it on paper. One of the bows was a take down that I wanted to use as the base for a one piece. This sounds similar, just opposite of what you want to do.
I would suggest that you follow your gut instinct of tracing the bow on paper and starting there. You will need to keep the geometry of the bow as close to the original as you can. Determine how you want to join the limbs to the riser and then design the limbs and riser accordingly. You will need to measure the limbs on your existing bow to determine the taper over the length of the limb. You will also have to calculate the butt thickness of the laminations. To do this I measured the limbs with calipers at three locations to determine the rate of taper. I then measured the thickness at the fade and then added the .002/inch for the length to the center of the bow. These measurements were taken numerous times to get an average because I was measuring individual pieces of wood in a completed limb that I was not willing to dissect. Realize that you will probably have to make a couple of the bows to get to your target weight. To keep the cost of development down I built my own lam grinder (Cost less than $100) and made my own laminations out of a local hardwood (Ash) I also made the riser out of inexpensive woods. It took me two of each bow to be able to accurately calculate thickness for bows from 30# to 60#. As far as the wedge, make one that follows the geometry of the bow you are copying. I wish you success in your endeavors. Failure is only achieved by not trying.
pete