I think it's time for a voice from the antipodes to adjudicate this lively and entertaining debate which raged on as I slept.
In the words, "dressed overall" the word overall is an adverb in that it describes how the mast is dressed. What we are seeking is a word to replace "it" a pronoun ... and "it" appears twice in the clue. Hence, the noun "bunting" seems more appropriate.
For what it's worth, my money's on bunting.
I think you all deserve an extra a round of rum for your efforts, so let's splice the mainbrace and weigh anchor on this one.