In my opinion, you can make any bow shoot "off the shelf"...you just may have to build the shelf up some. I've got an old Browning Cobra with a shelf as flat as a pancake...shoots like heck off that flat surface. Put a small 1/4" piece of leather on the shelf surface so it was the only contact point the arrow would have (directly over the deepest part of the grip) and voila...shoots great off the shelf.
It's true some bows of yesteryear were built to be used with a rest. A rest is certainly a cheap and easy alternative, but don't give up on making them work off the shelf. It certainly can be done.
Good luck!