Hello from Tampa Florida

[Peterbylt]

Thank You for having me on the forum.

Just finished upgrading my old Mongoose Full Suspension Mountain Bike with a Bafang 750 kit and a 13 AH battery.

I am really happy with the results, I am now riding the bike a lot more than I had before upgrade.

The only issue I had was the Battery would not fit in the Triangle, I fixed that by mounting the Battery on a rear rack I scavenged from a rotting beach cruiser.

Peter

[Retrorockit]

Welcome to the forum. FS bikes are always hard to find room for the battery.
My first suggestion would be to get a bigger/better front brake. 180mm Avid BB7 with metallic pads from EBC or SRAM. Maybe even 200mm.
My second one is the fork looks sketchy. I see the welded sheet metal cross brace. I would look for something from Rockshox, Manitou, or Marrzocchi that has cast Magnesium lowers and hydraulic damping. Worldwide Cyclery, Modern Bike, and others usually have deals. Maybe your LBS has something used. A lot of MTBs in FL never got ridden hard. Not all forks have the same brake mount. You might do them both together.
These are both safety and control items.

[Retrorockit]

There are triangle battery packs that might fit in the front corner of the frame.

https://www.ebay.com/itm/385231590748?hash=item59b197955c:g:Dj0AAOSwozpjcbye

They seem to have loops on all 3 sides. But I would ask to be sure.