No really. The Steel Claw's master of chirascuro, Jesus Blasco, really did do some stuff for the black & white Marvel mags back in The Bronze Age. Lifeboat! is from the 2nd issue of catch-all title Monsters Unleashed, while The Claws Of Tryphon comes to us via Vampire Tales #2.
Esteban Maroto also did a Satana strip as I recall, suggesting Stan & Roy initially attempted poaching all Jim Warren's Spanish stable off him, before settling in with thier regular team of artists.
Neither story is particularly groundbreaking, but who cares about that? Jesus Blasco could make a still life look like the moodiest, scariest thing ever.
Tryphon also comes with an unexplained handover to John Romita in the final four pages, which makes it doubly fascinating, watching Jazzy John trying to fit his style around Blasco's. He really was the go-to guy for eveything, wasn't he?
