That should do it assuming the battery is in good condition. Your other options are a pair of 7.2V NiMh stick batteries or a lipo with 3S or 4S, though that's a bit overkill and some starter boxes explicitly suggest against it.
I have a starter box and it definitely saves me a lot of effort, though ironically it usually only takes a second or two to start and then I'm running all day. It basically doubles the weight you need to transport to the bashing location, so means of transportation / distance of the walk becomes a consideration against the labor savings, especially if you're considering a lead-acid battery...