I found some pictures of my A123 battery packs placed in my truggy and buggy. As i'm at my girlfriends place i can not shoot some pics of those packs themselves.
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For more runtime you may look into a 12s setup. But 10s is convenient as a dewalt pack holds exactly 10 cells. When driving like in my previously posted video runtime goes down to 7-8 minutes with 10s1p A123. When drving more reasonably with not as much high speed passes and less grip i got up to 12 minutes out of my packs. It really depends on a lot of factors (gearing, vehicle wheight, driving style, surface ...). In my lighter buggy (9lbs) i could drive for up to 13 minutes when pushing it hard. So wheight has a lot of influence on how long you will drive.
You might have seen
this picture of legobrains FLM Savage which exactly represents how you will get your A123 cells when they are salvaged from a dewalt pack. Don't know if they will fit this easely in your savage. You only would need to solder two cables and shrinkwrap it. I wish it could be as easy for me to build my packs.
By splitting your packs in 2 5s packs or 2 6s packs you would be able to recharge 2 packs in 15 minutes when using a hyperion EOS0610iDUO Balance Charger. It also has 2 integrated balancers. A choice you might consider.