The first thing to do is determine if it is a grafted tree. As old as the tree is, this may be difficult or impossible as the grafting scar may be healed over and unrecognizable. However, look for a grafting scar or mark. If it is not a grafted cultivar, then you have a very nice acer palmatum dissectum. If it is a grafted tree, my guess is Brocade. The color is that red/orange color that Brocade has, and the leaf shape says Brocade all over.