Hi Bruce,
Jim Webb, who has owned over 200 original bags over the years, shared with me that almost all of these bags had leather straps. The ones that didn't he is not sure were originally made with a cloth strap. Just a thought. I believe it would be easier in the long run to make a leather strap than sew tabs and such to a cloth strap.
Of course, I am no expert at anything, so take what I say here with that in mind.
God Bless, Marc