I can tell just by looking at it, that the tree probably has rot in it. I'm betting a good portion of that tree is either hollow or really soft, by the looks of the rootball. By the looks of that picture, someone else has already been 'picking' the good stuff off of it, looks like a lot of the branches have been taken and that would have been the good stuff on that tree. yes, there is still good wood on that tree, but I'd venture to say the bigger part of that trunk is junk. Worth going and looking at it either way. I wouldn't be paying a single dime for that, as there is going to be a lot of waste wood if the trunk isn't any good.....
As for cutting big trees with a medium sized bar, it can be done if done properly and carefully. I would start at the top and work your way down to the rootball. When you get to the really big parts of the tree, I'd be cutting straight down through the round from the top (you standing at the log, looking at it from the cut end towards the root). Make a pass straight down through that point, as deep as you can get your bar into the tree. Then, go to either side and make a straight down cut. You'll end up with "orange slice" pieces, which you can take to your splitter and make your splits......
Let us know what you decide to do, and we like lots of pictures here, too.....