Castle set identification (photo from 1993)
I have identified a unique part, to help with search - Panel 2 x 5 x 6 Wall with Window with Window Stones Light Gray Pattern which has been used here.

It has been used in just two sets listed seen below, none of which look like your model
Black Monarch's Castle (6085) from 1988:

Black Knight's Castle (6086) from 1992:

So it seems like someone made a great MOC back in the days!