why don't you make whatever sized b/w print from the slide you want, the image will be a negative ..
THEN go to a copy shop and have an analog xerox made ... then take a cookie sheet / hot plate
and some parafin and wax the xeroxed negative to make it translucent. i have been making paper negatives for cyanotypes
this way, and the first black and white photographs / salt prints were made with paper negatives.
it doesn't take long to wax the paper, and it is kind of fun to be able to see your fingers through the paper
i have gotten good exposures in winter sun mid day and late afternoon at 40 mins maybe a little more maybe a little less
with an exposure unit i am sure it would be a fraction of that.
have fun !