You've done a lot of work on this thing! That chassis looks beef.
It looks like you track will be quite a bit longer than most. Don't forget that the longer/more ground contact you have the harder it is going to be to turn.
I've been thinking about the turning too, I wanted the tracks to stick out the front so I don't tip over forward with the loader, I am going to shorten the back lower sprocket, I'm going to put it right below the top drive sprocket.
This will shorten me up about one foot. I'm hoping it's going to steer, but if it doesn't I have a pair of heavy duty hydraulic drive motors with brakes and hubs already mounted. I could always set those up if this doesn't work.
Thanks for the help