Looking through some of the stuff from that era it all looks very geometrical and sharp angled, so maybe something utilising that, like taking all of the curves out of the standard faces, making them more simple and abstract, just made up of shapes. But then again part of me thinks if I am going for the casino style maybe they should have standard faces as all of those did.
I'm not suggesting a vast, drastic deviation from the traditional faces. Traditional is fine. I would suggest a few color tweaks, perhaps - just something to make them more distinctive from your ordinary pack of Bicycle Rider Backs. Many casinos switch the bright red of the standard faces for a deeper red - almost a blood red. I find it's easier on the eyes, though the actual reason for the change had to do with the black-and-white security cameras of the day - a bright red on a white background was difficult to spot and read, while a deep red showed up as a dark gray. Even today's color cameras catch the deeper color more easily. Perhaps that burnt red you're using on the backs would be a great color swap. You might even consider making the courts more monochromatic, using just black and shades of burnt red on white.
If you wanted to customize in any way at all, make it "minimally invasive" - for example, do you recall the "star" patterns that were a common decorative touch back then? They looked a little bit like jacks, even down to sometimes having little rounded bits at some of the tips of the "rays", and we often portrayed in a metallic gold or silver. You could design a few of those, but make them small and unobtrusive - about the size of an index pip - and scatter them pretty much at random throughout the cards of the deck, but just on the faces of the cards, and use metallic silver or gold inks. For the court cards, you could incorporate them into their clothing.
They'd also make a nice decorative touch for the tuck box, done in a metallic foil. I wouldn't go too crazy on the box, either, however - no embossing and little use of foil if any. It's not how cards were packaged then - you need not be slavish to the design of the era, but some authenticity in the appearance is called for here.