Hi, first let me congratulate you on an awesome project and on your recovery after neuro problems. About 25 years ago I looked at doing a similar project. The base car way back then was a series 1 Mazda RX7. I got a shell to use as a base and spent countless hours drawing and modelling. I intended to use polyurethane rigid foam and fibreglass over it. You might find this a useful technique for any areas that can't be cut and joined from your mouldings. It is super easy to sand with sandpaper and surfiles. It might free up some design decisions for you. Glue a bit of foam on, sand it to shape, throw it away and start again if you change your mind.....Here's the article on the process that got me started:
http://www.rqriley.com/frp-foam.htm
all the best
Ross (in NZ)