Yes. The way I envision it, "RuneQuest" would be an outline of the supported "options" (hit locations, et al) with perhaps a new option or two thrown in that the would support. In addition, a basic outline of how to cull, convert, and GM the HQ supplements like Sartar and the Sartar Companion, with a small bestiary of the common non-human and monster types, with a bit more space to PC worthy races (Mostali, Aldryami, and Uz).
Probably, all told, not bigger or much bigger than the core HQ book.
SDLeary