House ad for Marvel Treasury Edition #28 [Superman and Spider-Man] (July 1981); printed in Batman #327 (September 1980)
...which technically isn't a DC House Ad, as this second tale of Crossover-Earth (Earth-7642) was published by Marvel (altho' co-produced by both DC and Marvel), but it's close enough for a book in which this titanic battle happens:
...not to mention this one!
Panels from Marvel Treasury Edition #28 [Superman and Spider-Man] (July 1981), by these guys
Oh, and because it's in black-and-white in the ad, here's that cover in glorious crossover color!
Cover of Marvel Treasury Edition #28; layouts by John Romita Sr., painting by Bob Larkin