If you want to have a blade with a 5/8" hole enlarged for a larger arbor, the Heinemann saw company will do it for about $17.50 per blade (net).
At least, that's the price they quoted me to enlarge a 5/8" arbor hole to 1-1/8" for an old B&D hand saw.
I believe they sell their own brand of blades as well, but they'll enlarge the hole in any blade and they do sharpening also.
Of course, you'll have to pay for shipping if its not convenient to drop it off at their place in Ohio. USPS has a flat rate box that I think will hold a couple dozen blades (I can't imagine the Postal Service could make money on a box that heavy for $11 postage.

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I suspect you can find other commercial saw sharpening companies that will enlarge holes also.
Maybe some enterprising person could get a special rate doing a batch of blades and reselling them so at least they'd be available.
Contact:
Art Poorman
Heinemann Saw Co.
Phone 330-456-4721 ext 16
Fax 330-456-0318
Heinemannsaw.com