for the project you have in mind Mike I would choose ¼" Cherry plywood even though my preference is a solid hardwood (the widest width you'll find in a solid Cherry wood will be maybe 10" or 12" and difinitely not in 1/4" thickness). This will solve the size requirements saving $$ and time. Once the project is completed with finish of choice it'll look awesome. Longevity is no concern.
Terrific cutting of a very fine pattern Paul. As a suggestion (depending thickness of wood used) I'd try placing the portrait within a reddish brown or ebony frame with a white matt. Too nice of a portrait to set aside. Maybe others will have suggestions to help give you ideas to consider.
Can't go wrong on price. And operating ... well, you REALLY can't go wrong. With a little maintenance and polish you should have a decent backup. Great find Kevin. Please post an update photo after you have it looking like new ... Lol