+1 on plywood. The first time I removed the console in my KR, I thought it had to be a home-made concoction.
That was in 1982, when depth/breadth of '68 Shelby knowledge wasn't readily attainable. However, after sending some pix to Kopec, it was confirmed as correct.
But, wow...plywood in a Shelby. Remnants of an East Texas chicken coop?
Devil's advocate: Plywood is cheaper to make into a rectangle box, by humans, than is creating a specially-molded piece of plastic.
So, they built the console like a high school shop project.
Downside is the plywood adds a couple of pounds to the car's weight, versus plastic. That'll add 0.0002 seconds to your ET.
So, adjust your bracket race dial-in accordingly.