Definitely and interesting experiment, the limbs on that Hoyt are carbon with some glass on belly and back...nice.
Straight off I can suggest a very nice site > Thecrossbowmansden.com
It is Robin Allen's site and in the Hints & Tips you will find lots of info on building match crossbows...everything from pressing modern composite limbs of sport to hunting weights, to track dimensions vs shaft diameter vs #strands in a string vs point of contact with the arrow nock and it's preferred shape...really nice stuff.
Robin has been ill lately, so his friends have been posting his latest work that includes some interesting details of a reduced friction limb nock that your setup will definitely benefit from. >>>Link
I have a few questions if you don't mind
1. How did you calculate the 90lb at 30cm? or are these the limitations set by the sport rules that you are palnning to match these hoyt limbs to?
2. What kind of arrow track will you be using on this one? What material?
3. Will you be making the sights too? or using optics/bought sights?
4. Well actually(1.)
What tournament is this crossbow is being made for? Shooting distance?
Definitely an interesting project, looking forward to hearing/seeing more.
Good Luck and again Welcome!