Guillermo del Toro will have a busy fall promoting his new movie “The Shape of Water,” but he’s squeezing in time to plug another project that’s not his own: Dario Argento’s expressionistic horror classic “Suspiria.” As a guest curator at the upcoming 50th edition of the Sitges Film Festival in Spain, Del Toro will curate a series of Italian gothic and giallo films, but he’s particularly keen on returning Argento’s work to the big screen.

“Dario especially needs this now that we have a little historical perspective to position ‘Suspiria’ as the work of pure madness and cinematic joy it is,” said del Toro. “I think it’s very important to celebrate his place in history.”

Argento’s ominous, tonally complex work follows an American ballet student (Jessica Harper) who enters a German dance school that turns out to be a haven for witchcraft. For many genre aficionados,...