Unless I'm not following the OP's explanation, badmother, he doesn't need a quill bottom: the bottom part of the stem riser, the part with the hinge, is what fits into the head-tube. He has that. The tube he needs must slip into the bottom part of the stem, where it will be held in place, at the desired extension length, with the QR clamp. Any standard stem with a 1" hole could slip over that tube and be fastened with bolts.