A couple of things come to mind on this issue, no particular order I guess.
One is; most Cobras don't see a lot of miles and anything mechanical that isn't used so much goes down hill just sitting there! Fuel gets old and funky and messes with the carb. Now about that carb, many guys spend a LOT of time "playing with the carb" in search of that illusive "perfect tune". As many of us are running fairly healthy "race" cams seeking the perfect carb response is like chasing rainbows. Your always "almost there, but not quite." EFI is often times much worse to dial in!!! You want "perfection" with your fuel system? Do a near stock 302 with factory EFI and computer. Ford has spent millions of dollars and thousands of hours "dialing in" the software so you don't have too. The minute you rip that out and go with a "carb" or an after market EFI system, there goes your weekends. It could take YEARS to eventually stumble on "perfection".
Double pumper? Center Squirter? Center pivot float? Vacuum secondaries? What cfm? Jets? Power valve? The combinations are as endless as the world of replica Cobras!
If you don't want to spend so much time with a carb, keep it real simple. Buy a NEW (never used) Holley vacuum secondary without adjustable floats, one PV and one metering block. Keep it around 650 cfm, enjoy more weekends free.
Simple and inexpensive and mostly bullet proof because there is not a lot of adjusting you can do to screw it up. Works well for most engine combo's right out of the box!
Ignition systems; no easy way around it. Subject to high temperatures and moisture due largely to the car "sitting" to much. Self wired, it's easy to screw up the wiring, it's easy to BLAME the ignition when it may not even be the problem! So that takes you back to the carb, which if it was setup OK, is usually NOT the problem. Many of these "problems" we bring on ourselves, in search of 4 more horse power...
I know a guy who has over 60,000 on his Roush 427 small block (CSX-8000 car). He does carry a spare carb around with him though. I've seen him change carbs a few times, they can be nasty little buggers to sort out. But he's clearly in the ball park, with 60K on it!!! He put a 100,000 miles on a B&B with a 351 Cleveland before he got the CSX. Built them both himself. He is NOT looking for that illusive 4 more horse, he is after smooth and long life and has figured it out, so it can be done! His car never "sits", thats a big part of it.
...now excuse me, I've got to try a new combination of power valve and jet size on my carb. I'm pretty sure I can pick up that illusive 4 more horse if I stay with it another 6 months, or until I blow up the motor,,,, again,,,
But if it does blow, thats OK, there some new combination of internal "stuff" and "tricks" I've been wanting to try out. In search of the perfect side oiler 427 stroked perfection, an illusive goal, but I'm tracking it down.
Oh yeah, CORK gaskets, I could never get the rubber ones to work. I use cork, ONCE, throw it away, buy new ones every time I adjust the valves (which is a lot actually).