thanks for the feedback, all.
for bill:
subterranean termites hollowed this old casuarina out causing the tree to go down during a recent storm. considering the labor involved with hollowing something this size. I doubt I'dve taken on the project hadn't it been for the termites.
lying ahead is more rough carving around the trunk to create "roots" then leveling at the top and bottom. the bottom will be carved to create legs. the top will be fit within a compatible slab shaped to appear a part of the original trunk. then lots of finish carving, sanding, etc.
there's no book on this, so its bump your nose and go !
best wishes, sam