Except the 748s are just that much smaller than the 747s. They didn't fit. Now that was ok, because I could still return them to Zappos.com where I'd bought them from, but I still really needed some new shoes.
Memorial Day evening, I went on-line at Zappos and ordered a new pair of New Balance 965s in a wider width. They've got next-day delivery included in the price, but -- of course! -- they couldn't ship on Memorial Day in any case.
So the shoes shipped on Tuesday morning.
And arrived on my porch on Tuesday afternoon, much to my surprise.
My left foot feels much better.