This issue is a variant of Captain America (Marvel, 1968 series) #197 [25¢]. There exist further variants.
Marvel Comics Index #8A lists letterer as Gaspar Saladino. Verpoorten credit by Nick Caputo, August 2012. Previous indexer credited Frank Giacoia.
The Madbomb Part 5.
Letters from Ralph Macchio, Gregg Stamey, the Marveriter.
Marvel Value Stamp Series B #78 "Conan".