I did some pushing and shoving and the benches are in place. Other things need moving such as the drill press and the swamp cooler but the shop is useable so I can finish the bench. First up will be pegging and Spaxing the slabs to the base followed by making a split "fill and tool holder". I expect I will cut the slab to length before installing the lower shelf on the stretchers and someplace in there will be a coat of BLO.
This photo shows the old bench in place with the back side of the new bench. I will re-install the leg vise on the old bench and will have two fully functional benches along with a sharpening bench on the other side of the shop.
The working side: