Can you do any work yourself, or are you willing to learn?
Shops are expensive. I know that I get paid well to work on people's cars. I'm an independent retired guy who occasionally fixes a few Speedsters, Spyders, and sand rails.
First: the trans leak. It's a 5 year old car, not covered by any warranty. Where is the leak? Depending on where it leaks, it could be cheap to fix(axle boots, wheel seals out by the brakes, or maybe a shift-shaft seal). Even an input shaft seal only requires the engine to come out. If the leak is from the gear carrier, I'm sorry, the engine, then trans has to come out and be re-sealed. I don't know how much your mechanic's shop rate is, but I'd guess 16 hours would be enough for the trans R & R and reseal.
Carbs: Rebuilding the carbs shouldn't be more than a few hundred bucks plus rebuild kits. The more important thing is why are they leaking? Sounds like your fuel pressure is too high. Solexes: 1.5 lbs., Webers: not more than 3.5 lbs.
Valve spring: Sounds like bad luck. It could be an easy replacement. But not on my engine. I'd have to pull the head and inspect the chamber, piston, and cylinder walls. If the engine was pounded to death after the valve spring break, I'd rebuild the whole thing, including new bearings and splitting the case.
If the engine was shut off immediately, less damage should be the case. It might only be one pushrod, one rocker arm, and a valve/spring/retainer.
Mark, you may be done with major problems for a while. Maybe not. Things happen on these cars, if you drive them.
If you're OK with that, carry on. If not, go buy something mainstream that will scratch your itch.
Welcome to our crazy world. Spend money like water. Come on in, the water's fine.