Given #3, in retrospect, I should have spoken up sooner to keep your expectations and disappointment in check.
DEFINITELY go longer on the GC!
On the bright side, you got a killer deal. Since you already have your old pack out, build yourself a discharger:
and discharge it. The above is about $4 from Hope Depot. The board is one of those screened fascia pieces for ventilation. Yank the screens out, and you don't have to drill the 2" holes in it. They're $0.98 each.
If you measure voltage and current, you can estimate your pack capacity.
Good luck!
Steve