Ford Think Li Batteries Upgrade

Hello fellow Think owners.

I just got me one and it’s in need of some TLC. My Deka Dominator gel batteries are not in a great shape. I’m considering going down the Li route if the investment is reasonable and provided I don’t end up in a deep rabbit hole, due to my very limited skills. BTW, I’m installing a 6hp and a Rev 2 controller as mine is still has a 4HP and Rev 1.

What are the parts needed for a successful Li upgrade and what would be the approximate cost for the complete project?

Thank you