King Hery VIII lived from 1491 to 1547. The earliest documented evidence we have of the feilidh-mor (belted plaid or great kilt) is from 1594, and we don't get any information telling us much about the length of those garments until much later than that.

The origin of the "7 to 9 yard" myth is most likely from extant eighteenth century military records that do denote these lengths being used for belted plaids, but in single width (usually 25" to 30" wide). This cloth would be cut in half and the peices sewn together to create a double width plaid. So a "9 yard" felidh-mohr would end up being 4.5 yards long. From what we know, 4 yards seems to have been about average.

If you are planning out how to pleat your feilidh-mohr to either sett or stripe, you are really over thinking it. These are modern pleating forms used in tailored kilts. (Pleating to the sett, in particular, wasn't used until the very end of the nineteenth century). The belted plaid wasn't even so much pleated as it was gathered.

You may enjoy reading my article on the belted plaid here:
http://albanach.org/kilt.html