Hi Eric. It sounds like you've been bitten by a bug that never stops until it's eaten you up. <g> I've been there; I have an original edition of Costin and Phipps book, and a contemporary that I bought in 1961 -- _Sports Car Bodywork_ by Locke. Over the years I've built a near-bookshelf of bodywork, chassis, and engine sports-car and race car books.
I've helped out on two such projects by others, neither one completed. I'll suggest that it's 5 to 10 times as much work as most people, even experienced metalworking people, think.
You probably don't want to hear this, but my suggestion is to buy a good kit car that you like and build that. There will be plenty of work to do, for a year or more, typically. If you're really lucky, you'll find one that someone half-completed before they gave up. Those toys have left broken marriages behind. It's sTILL much more work than most people realize.
I've gone to great lengths to try things -- hammering aluminum, welding 4130 tube, and so on. When I did some sports car racing in the late '60s and early '70s, I rebuilt two Alfa Romeo engines, and tuned Jaguars, Triumphs, hot English Fords, and Bristols (AC Bristol cars) for my sporty-car friends. I had an excellent English mechanic for a friend and teacher. Out of college I first worked for Ranger Yachts, as a fiberglass layup man. It's MUCH easier to learn than hammering aluminum.
I raced an Alfa Romeo Giulietta Spyder, an MG Midget 1275, and I drove or owned many others. My old college roommate still has one of the 50 Lotus 7 Mk IVs that were brought into the US in 1971. I've driven it; even though it's the most advanced chassis in the Lotus 7 series, it's still twitchy. My MG was more stable. Suspension and handling are exceedingly tricky on a scratch-built car. That's why many of the English club-racer specials took the suspension parts wholesale from some proven car. The Triumph Herald was a favorite.
Carbs are manageable. There is a good book on tuning SU's that I used to use. I've tuned Weber DCOEs for hopped-up engines, and sliding-throat Zeniths. Just read what the experts say. SU's, particularly, have so many combinations of main jets and needles that you'll be completely lost, if your engine has even the slightest modifications, without a good book. There aren't many "experts" left to call upon. IIRC, Clare here on the NG should be able to steer you to info sources.
Good luck. I'd love to see some beginner tackle a start-to-finish sports car and succeed. Something really simple, like Champion's Locost, gives the best chance of pulling it off. Beyond that, it becomes distressingly complicated and frustrating.