Sam, I will send yours on Monday.
For batteries, I would not modify that frame of yours. If you go 18650 Route you will probably fit 1500Whs in there. If you give me the dimentions of your stock pack we could count. You stock battery will work with new controller but you will soon feel that you need more power and range from the stock battery because you will pull more power from the new controller - less range.
As for the motor, it depends. Your current motor is light and that is a plus. Will it be a road only machine? In this case the weight is not crusual and you can go for the big boys, like:
*Cromotor (you need 165mm drop outs)
*Crystalyte crown (lighter than cro but not as powerfull)
*Even more lighter, maybe the new Crystalyte TC4080, it is a newer version of your old one.
*New, cheap and popular MXUS 3000 (https://endless-sphere.com/forums/viewto ... =2&t=63142
But that motor needs more optimizations before the perfection, like thicker phase wires, better axle, thinner laminations(they are 0,5mm now) and a cast stator instead of a staped one.