I loved Shaker Beige on the color palette until I painted my bedroom with it. I'm sorry to say that it looks like gray/green mud. My husband finished painting, I walked in and both of us said what a mistake. It's like sleeping in the mudroom. Sorry, I can't be of any help. It's a totally boring color in my book.

It sounds like such a neat project. I have found when I cut out my pictures(like around their heads,etc.) that I am never happy with them and wish that I hadn't done it. I see cute layouts with them cut out but it doesn't work with me. I don't have a scanner but I don't know if you scanned the photo if you could lighten anything up. Do you have negatives that you could take in to a photo shop and just ask for advice. I had my daughters graduation picture with her cap and gown and the dark gown just blended in to the background so I mounted it on white to try and lighten it up a little. Good luck.

I still would take it to a professional framer and take advantage of his experience and advice on matting and framing. That's his business. I have an abstract print in my traditional home and the frame shop help was exactly what I needed. He double matted in colors that are in the print (similar colors to yours) and framed it in a simple very narrow gold metal frame which made the yellow/orange single cIrcle in the print (like your yellow one) really pop. You have nothing to lose by getting experienced advice. Just make it a one stop trip and you will be able to sit down while trying different matting choices and ideas. I do think your original dark mat is the direction to take, using a dark color from the print itself and then a very simple gold metal frame. The mat does need to be larger, too. The golden yellow mat does nothing for me and on my tablet doesn't go with anything in the print at all, but seeing it IRL may be different.

If you want modern frames you can find metal component frames from Dick Blick online. You order the sides separately and they screw together in the back. But glass will have to be sourced locally (as it always will when ordering online - most larger framed art does not ship with glass).