Many of us are not fans of spring loaded chain tensioners. They allow too much slack when you need it the least. On a swing arm rear suspension you're going to need a lot of tension adjustment, constantly.
A jack shaft, or shift kit might be an alternative but you'll still need to keep the chain tight as the suspension swings in its arc around the pivot point. Is that a multi speed rear hub?
Just a word of caution if you've never ridden a bike or motorcycle with that much fork, it can be a challenge until you get used to it. Once you get it running take it real easy at first until you master the odd steering you're going to see. Going down the road straight ahead is fine. It's curves and turning that can get hairy, especially the sharper ones.
Tom