Yes I agree these are awesome cars but I estimate one could sell a whopping 5 units of electrically powered versions a year...maybe...
I think the right way to make a business (i.e. Not a hobby but something that can pay the bills for you and 10-20 employees) is what OP suggested - offer high performance conversion services to the current owners of high performance gasoline cars - bmw, porsche, mercedes, audi. You probably need a 40-50k starting point in price of the original vehicle for your market to self-select in the right way. Then you need to pick a very limited number of models (maybe 2-3 max) to streamline your production and reduce marginal costs.
Can be done but not with kit cars imho.