Last year I was looking for a piece of pipe organ music I could use to play a cornet (one of my favourite stops, BTW). I finally found the Fantasia in d by Abraham van den Kerckhoven. Sheet music is available through the International Music Score Library Project. It’s the piece at pages 69 through 71 of the scan, or pages 87 through 89 of the PDF.
There’s a great recording performed by Nico Declerck. He plays it very accurately.
I found it hard to read in »Werken voor Orgel«. For example, there is no separate row for the pedalboard, and the awesome solo line is just a series of many sixteenths, not structured by slurs or caesuras. Thus I rewrote the score using the excellent Muse Score notation software. My release contains a PDF and the Muse Score source file so anyone can easily taylor the layout to her likings:
Have fun playing!