I recently discovered this cover recreation by Mike Ploog on Romitaman:
It's a recreation of Frankenstein Monster #6, the last issue of the series that Ploog illustrated, before moving over to Man-Thing. This is a big improvement over the original cover:
Published in 1973, it looks to me like the original cover was penciled by Ploog and retouched/inked by Romita. My guess would be that Romita wanted to portray that monster as being much more fierce and upset over his captivity. It just doesn't jibe with the rest of the cover, which is clearly drawn in Ploog's style.
The story inside is pretty decent as well--the Monster has survived 100 years after his creation and discovered Frankenstein's ancestor still lives in the area. Ploog plotted this tale in addition to providing full pencils and inks. Pure Ploog! Nuff said.