Good luck with your project, but I think you may find a few impedements that weren't there for the Jeep recreation. First, you can't buy all of the Porsche parts to do a true recreation as nobody makes things like new bodies, etc. Real Porsche parts are waaaaaaaaaay expensive. If you're willing to stay closer to the "looks like a duck, quacks like a duck" paradigm that the rest of us have followed, there are tons of places that'll sell you Speedster kits and associated parts. Remember, the Speedster replicas use Volkswagen mechanicals. These mechanical bits can either be original parts that have been refurbished, or new recreations. Do a Google search for VW parts and you'll find many companies like Mid-America Motorworks, Cip1.com, CB Performance, Chico Performance, California Speed Parts, NLA, Stoddard, Klasse356, etc. As for kit manufacturers, look under the makers tab above for links to Vintage, JPS Motorsports, Special Edition (Beck), Specialty Autosport, Thunder Ranch, Intermeccanica, and Street Beasts. The latter is not usually recommended on this board, but if you want to build from close to scratch, they are the most likely to be able to provide you that level of kit. The others tend to be more complete as purchased, and a couple of them only do turn-key cars.
If you are in the northeast (or even if you aren't), you should come to the Carlisle Kit and Import Show in May. There you'd be able to meet several of the manufacturers and look at cars from every one of them. It's a great place to do a lot of study in a short amount of time.
Oh yeah - welcome to the madness!