Sal Buscema credit per Rich Donnelly, Karl Mattson, Steve Whitaker, Nick Caputo, and Bob Ford. Confirmed by Sal Buscema. The original indexer and Carl Gafford credited Don Heck.
Inks and colors:
Roy Thomas and Bruno Andreacchi stated (http://errors.comics.org/show_bug.cgi?id=4233): Tom Palmer on both
Sources for letters credit are The Official Marvel Index to the X-Men (Olshevsky 1987), The Official Marvel Index to the X-Men (Ward 1994), and Official Index to the Marvel Universe (Vandal et al. 2009).
Sunfire's next appearance is in SUB-MARINER #52. Palmer coloring confirmed in letters page.