I have an aluminum CSX (4145) and LOVE it. The 427 side-oiler is precisely the engine I wanted- the small-block cobras may have been legendary and better-balanced, but the 427 is what gave the Cobra is legendary hairy beast status. I wouldn't mind having one of each, come to think of it. Anyway, the one on BAT seems like a good potential option for you. The wheel combo is easily remedied- nothing a bit more money can't quickly fix. You'll need a brass or lead hammer and safety wire-twisting pliers, and a few minutes watching some Youtube tutorials (I did one myself on my Instagram page), but that is all part of the experience of having one of these legends. I highly recommend the AVON tires. You can find a thread I posted on ClubCobra recently detailing me upgrading my tires to Avon's, but having the "billboard" style Goodyear lettering professionally applied after shaving off the Avon markings. This was a compromise with my son, who insisted on the Goodyear billboard look, but I REALLY wanted to try out the Avons (and we are both very happy).
As for the oil drips here and there- I highly, HIGHLY doubt you will ever find a Cobra that is completely dry underneath, unless it simply was never filled with fluids. I'm usually just grateful if ALL I see is a little engine oil. A drop (or more) of differential fluid is also pretty typical. I had a small coolant leak last year that turned out to be my water pump going bad; $300 and a couple of hours later it was fixed. They're easy peasy to work on, but honestly I don't think a 427 side-oiler is a great choice for somebody who doesn't like tinkering. Every few trips out on mine, I check the torque on the rocker shaft studs and take a quick "feel" of the valve lash, and every few hundred miles or so I set the valve lash. Granted, I don't put a ton of miles on it just because there are several toys in the rotation (a blessing that I know is ubiquitous on this forum). If you want a more maintenance-free engine, find one with a 428 (hydraulic lifters), or a small-block car (260/289), or whatever floats your boat (all sorts of builds out there with LS engines, 302's, 350 Chebbys, etc) but it sounds like you are after exactly what I would be after. One nice thing about a fiberglass car would be less stress about working on it and leaning too hard against a fender, and I'm always a little stressed at car shows with mine, hovering near the car to make sure somebody doesn't lean on it.
I was going to chime in earlier, but I saw that Tony, as usual, was very generous with his time and vast experience in the Cobra world and gave you all of the pearls.
Good luck!
Clint