Nice looking worktable. Looks very solid and strong. I built mine out of the same I-beam stuff. As to your battery selection for the Briggs. Being an RC'r from as far back as single channel escapement controls, I would not recommend a Li-po battery. You & I both know how prone to fires they can be. Go with LiFePO4. I made a battery pack from 32700 cells that is really working well on my engine test stand. I even charge it with an old FMA Cellpro charger through balance wires. Super stable voltage and plenty of power. If you don't have much amperage draw in your electrical system, a 4-cell setup should be ideal.