I use a series 31 battery for my Endura 55. I have a 14' Collins Craft. Its a fiberglass flats skiff. With two men in the boat, we have run that little trolling motor ragged. I think with a good deep cycle you can probably get away with using it.
But, the Endura is a speed coil design. That mean that no matter what setting you use, you're still using the same amount of power from your battery. I'm not sure what your old motor design was. I don't know if it had a digital maximizer or not. If it did, then it used up to 4/5's less power than the one you're about to start using.
Quit complaining about the color, just pull up your skirt and fish! -- snagged