My source for gogmagogical is Nares, Robert, A glossary; or collection of words, phrases, names and allusions to customs, proverbs, etc., which have been thought to require illustration in the works of English authors, particularly of Shakespeare, and his contemporaries, New Edition, Vol I, p. 376. London. John Russel Smith. 1859.
See also: Hyamson, Albert Montefiore, A Dictionary of English Phrases London and New York. 1922. p. 162.
Muret, Eduard, Encyclopædic English-German and German-English Dictionary, 1900, p. 982.
The entry for "Giants of Guildhall" in Nares' dictionary cited above informs us that the two enormous statues in the Guildhall of London were named Gogmagog and Corinaeus. The entry contains lines from a British broadside printed in 1660 that mention these two mythical giants.
"And thus attended by his direful dog, The gyant was (God bless us) Gogmagog.
A true curiosity. Aside from a music company called Gogmagogical Records and some plainly playful uses the only instance of this word I can find is the one cited by hernesheir. It may be Talyor’s own coinage based on the biblical Gog and Magog. That is a more complicated pairing than I had realized but I’m guessing in the context of the citation it means something like “all encompassing.” See more at Gog and Magog .