I think the Aussies amongst us will be horrified that you've overlooked Neil Hawke, Graham McKenzie, Alan Connolly and Johnny Gleeson
Actually forgot about Connolly - he was a decent bowler and fit to rank with the Holders and Sajjads. Hawke had finished by the time in question however and Gleeson had already been worked-out. McKenzie as I'm sure you know was utterly woeful at the end of his career. I maintain that their attack in the 1969/70 and 1970/71 seasons was very probably weaker than several county attacks around the time.
You're on stronger ground with Pakistan but I still think Salim Altaf and Intikhab would have walked into Lancashire's side and don't forget Asif Iqbal was a fair bowler in his early days - some youngster called Imran Khan started in 1971 as well
Imran was hopeless and shouldn't have been picked in either 1971 or 1974 though - he was a lesser bowler than Asif Masood at that point. Salim Altaf I confess I don't really know much about but if he was behind Asif Masood he couldn't have been that good - yet or by then at least. Intikhab Alam and Asif Iqbal were decent part-time bowlers and no more for mine.
but you may be right about the WIndies - for a brief period between Hall and Griffith at the end of the 60's and Boyce in the early 70's there was just Vanburn and that Sobers bloke leading a pretty threadbare attack but it was only really weak in the 70/71 series aginst India
An old Jamaican guy I know always swears that Uton Dowe was the worst bowler ever to be selected for Test Cricket - an 11th Commandment was added apparently - "Dowe shall not bowl"
Dowe was actually a bowler who appeared to be coming-up well and certainly not even a bad piece of selection - he started his Jamaica career well, played 3 Tests in 1971 and 1972 for 1 good, 1 bad and 1 moderate. He then had an utter horror-show in the First Test against Australia at his home ground (hence the Dowe Shalt Not Bowl commandment poster which ranks with No Cummins No Goins as the most pithy banners in Caribbean history) and never recovered. This game was indeed apparently as bad as any bowler could really expect to be (comparable to Harmison and Plunkett Old Trafford '07, McCague 'Gabba '94/95, Patterson Thompson '96 and '96/97, and the like) but was not representative of his whole career.
There were plenty of other awful bowlers around that time as well though - and this featured the time between the 1968/69 tour of Australasia and the 1973 home series against Australia. Threadbare throughout, for a whole 5 years - certainly not just a single year. This period featured a well-past-best Hall and Griffith, Holder who wasn't as good at that point as he would be later, Sobers who was past his best, the aforementioned Shillingford, Barrett, Inshan Ali and Dowe who were all awful, plus John Shepherd and Jack Noreiga (for a single season) who were decent, plus others who were every bit as bad as the aforementioned: "Prof" Edwards, David Holford, Raphick Jumadeen, Elquemendo Willett, there'll be others I've forgotten and CBA to look-up.
When Holder upped his game then Boyce and Julien appeared and Gibbs roared back to form, things looked-up very, very quickly indeed. But between 1968/69 and the home spring of 1973, no-one should underestimate just how bad WI's attack truly was - uniformly so.