[Ulzgoroth]

You seem to be posting in the right place for your questions.

GURPS definitely could be a good fit to the setting, insofar as you've described it. You may want to look for fitness to what you look for in a system besides setting support, though. I'm definitely pro-GURPS, but there are very different games that could also do your setting.

It's fairly likely you want GURPS High Tech, because that's where all the general (real-world) gear of the dieselpunk era would be found.

I'm not sure what the best source would be for raygun gothic elements. Tales of the Solar Patrol comes to mind perhaps, but you'd be mining parts out of a whole setting that you mostly wouldn't be using. You could, of course, invent your own stats for the superscience bits. Ultratech, which is roughly the SF gear book, may not be very helpful.

If 'golden age of comics' includes super powers you might want GURPS Powers (for rules support) and/or GURPS Supers (mainly for genre advice, though it has some rule bits that could be useful). You don't necessarily need either, though, you can pull off some super stuff, especially 'low' supers, with the Basic Set.

I'm pretty sure it's pronounced GURPS.