There is a way to use this without glass.You need to buy clear mylar in a sheet big enough to completely cover the vacuum board. Center the paper and neg on the board with the pump running and lay the mylar down, rolling from one side to the other so you can ensure the film stays on the paper. Using a soft cloth or a brayer roll any air bubbles out from the center of the sandwich. Give it time to pull it all down, you will be able to see it happen. Do your exposure and carefully put away the mylar. Best to keep it between two sheets of mount board as any kinks or scratches will show. This is also prone to static so use precautions to keep trash away and inspect carefully as you use it.
The vacuum board is really better for under the enlarger for borderless prints. You will need to lay scraps of paper or film over the unused holes to kill leaking air and get the maximum hold down during use.
This is a great find, are you going to try to make a ULF camera from the rest of the copy camera?