I have been planning a similar project off-line. One concern was lack of a reverse gear. Apparently Goldwings had them, or you could rig up a small motor to the axle.
Get the smallest front brakes you can find because it's going to be quite light. Maybe buy a CRX for all the little parts- brakes, gauges, steering rack, suspension? VW Rabbits also have tiny brakes and are not hard to find. They have McPherson struts however, which is worse for handling.
For suspension geometry, read up on some Lotus 7 replica forums. There are suspension calculators that will tell you everything you need to know. I've been considering a Ford-style twin I beam setup that would be very simple and hopefully durable.
What are you thinking about for the actual body? I am planning on custom building a body out of fiberglass, allowing me to design a bespoke (and fully faired, awesome looking) body. Windows will be of lexan or similar.
I don't know how artistic you are but if you'd like help on the styling front give me a holler. And keep the wheels forward or it'll look weird!
An early stage of my model. I've lowered the H point and will probably abandon this package.
Does anyone know the ins and outs of legalizing a custom built vehicle like this? It's obviously not a "replica" so at some point you're going to have to pass an inspection. What would they look for?