I have faked short steerers with a Steel tube type quill stem raiser..
The one with a 1" OD on the bottom will work.

crank the quill wedge tight , then up top, put the star nut in. Upper OD is about 9/8".

NL's BBB's BHP 21 is a more sophisticated Piece . they had a Quill bolt custom manufactured for them
(in Taiwan of course) it is internally threaded 6mm inside the 6mm hex used to tighten the wedge.
to be a part of the piece.