Cover appears to have been copied from a John Byrne drawing which appeared in the 1979 Marvel Comics Calendar, as character positions, clothes, and all other details are identical to the Byrne drawing. Byrne states he was not aware at the time that his drawing had been copied for this cover.
Both are reinterpretations of the cover from The Incredible Hulk (Marvel, 1968 series) #176.
'Part 1' added as an additional title and credits removed from the 1st splash 'title' page from #175.
'Part 2' added as an additional title and credits removed from the 1st splash 'title' page from #176.
'Part 3' added as an additional title replacing one of the caption boxes and credits removed from the 1st splash 'title' page from #177.
The reprint is minus 2 pages, as pages 2 & 3 from original story were re-worked as a two page pin-up which followed straight after. See next sequence 'Bonus Hulk Pin-Up!'
Pages 2 & 3 from The Incredible Hulk #177, which consisted of a two page recap with a new montage of images and caption boxes describing various recent storyline events, with all text removed and used as a pin-up.
The 1st 'title' page has had panels 2-5 removed (the recap of Warlock to cocoon scene) and the first panel has been enlarged to fill the whole page with the removal of all caption boxes and credits (just leaving Banner's thought balloon). The title has been re-jigged and 'Part 4' added as an additional title.
Covers from The Incredible Hulk (Marvel, 1968 series) #175-178 in black & white/grayscale.