You have carved a really heavy relief and are thinking about how to hang it on your wall...
For me, the usual method I'd use is to put 2 hanging fixtures on the back of the carving so the weight is divided between 2 points on the wall. And my usual 'fixture' is an escutcheon plate - you can see me using escutcheon plates in the Koi carp project here.
Now, the escutcheon plate fixing, whilce a strong and safe way of holding the work, requires you to position the wall screws very accutately. Also, because the hole in the escutcheon pate is small, you find yourself fumbling around with a heavy weight as you offer the carving up to the wall and try to locate the screws, which you can no longer see!
This is one solution I sometimes use. You have a bigger hole to offer to the wall screw and some lateral give in positioning.