Penny wise and pound foolish idea. Replace them. It’s the only way. You can’t alter old site built cabinets like that. They aren’t built to modern cabinet construction standards.

Problem is the upper cabinets are great. They're tall, custom, I already stripped many, many layers of paint from them. I want the lowers to match and can't buy cabinets like this anywhere. What you get in is expensive real wood, or the particle board with a facing that would look horribly out of place in an old kitchen like this.

You have sunk costs in your labor. There is no going back and making a better decision that would recoup that spent labor. It’s gone. It doesn’t improve the situation moving forward.

You’re still going to need to replace those cabinets. Unless you yourself are a cabinet maker and can take all of the faceframes pieces apart, and refurbish them, and build modern boxes? And you’d have to not put a value the labor at all. Which is what you‘ve been doing. Sorry, but time and effort both have a value. And it’s far more than the worth of those old cabinets.

You’ve spent your time unwisely. Don’t continue to do so.

How about mixing and matching the cabinets? I'd keep the uppers and change the lowers and change all hardware to match. My plan was to paint the uppers cream and lowers a dark green anyway.

You beat me to it. 😄

How about the window overhang? Is that a problem r just something I have to deal with not being perfect?

Where do you live? Find a Shiloh dealer in your area to help you figure out the best way to go. Or any dealer/cabinetmaker that will do a 3/8" Offset Lipped Door to match what you have. A flush inset would be an OK alternative or a partial overlay slab door. The LIPPED door looks thinner and less bulky. But if you do partial overlay lowers (slab door) and keep your lipped doors on the uppers...that would look good too.

With Shiloh or any other semi-custom or custom cabinet, you can do custom depths.

There’s a big difference in quality between higher end antique inset cabinets, and “vintage” old rabbited 3/8” lip plywood doors. One inherently has value. The other does not.