Convert Floor Standing Speakers to Bookshelf Speakers

I have a pair of Mission 773 floor standing speakers. They sound great, but the finish (black wood effect vinyl) has started to peel off, it is possible the previous owner let them get slightly damp or the material has over time become too tight and come off on its own. I think it's called Sheffield Oak Umbra Vinyl Fablon.

I am thinking of rehousing them in a smaller enclosure so that I can fit them on shelves. My question is, if I maintained the distances between the different speakers in the new enclosure, will a new enclosure be detrimental to the sound? I would like to go for a black wood finish, which shows the natural wooden texture. What wood should I use and what thickness? What do I do about feet?

 

How about something like Oak Crown Cut Plywood MR Veneered 1 Side Only ?