What about putting some of the plywood on top and back of your existing bench with carriage bolts? Then run some screws threw the piece on the back into the wall studs in your garrage. Or do you think the frame of the bench is to cheesy?
I ordered a bench top beam from QB here in Salmon.A laminated beam of 3.125" x 24" x 12 foot was $87 and is beautiful.
Only problem is when I don't use enough lube on the brass case it causes the whole table to jump.