Thoughts about Independent Rear Suspension
Personally, for the cost this will surely involve, you are creating a VERY limited market. Serious drag racers probably won't want them, some of the vintage autoX racers can't use them as to class rules, and a huge majority of us can't afford them.
I have to give ANYONE who has the talent to pull this sort of thing off, "big credit"
Maybe a different approach would be to offer detailed plans / blueprints, and offer to sell the hard to make pieces