This is a funny coincident. I've always loved these Sløgedal variations. My father did in fact record these variatins in 1982. He was the organist of Sct. Catherinæ Church in the town of Hjørring (Denmark) until 1998. And he played it on a Marcussen organ (Marcussen & Sons, Aabenraa, Denmark).😊. He and Bjarne Sløgedal knew each other for decades.