You are getting closer. I have been following along, getting ready to start my own soon. I build a bench to build my bench on, my wife asked “why don’t I just use it?” The quick built bench has a 2.75" thick plywood top and 2×4′s with lag bolts for the edge and stretchers. With reclaimed 6×6 posts for the legs. I just finished gathering and planing the wood for the new Roubo to come. I am using red oak for the legs and hard maple for the top. I will be using your dimensions roughly, it’s going to be pushing 400lbs I think!
CHRIS, Charlottetown PEI Canada. Anytime you can repurpose, reuse, or recycle, everyone wins!