Thanks for your help. I confess I hadn't tried all the variant spellings of his surname. That's a good strategy for netting a broader array of results. I'll flag his entry as a possibility, even if it's just a slim chance they're one and the same.
Peter's sons were involved in lead and iron-working in Manhattan and Brooklyn, and got rich by selling to gold rush prospectors and manufacturing weapons & ammunition during the US Civil War. They shipped goods and raw materials from New York to an associated foundry in San Francisco. I was wondering if these Naylors might have been related to the one who ran an iron import firm, Naylor & Co. (or Naylor, Hutchinson, Vickers, & Co., or Naylor-Vickers) which was founded in Sheffield, England in the late 1700s, and set up an office in New York in the 1830s. The firm got attention from the government in the 1870s for cooking their books and falsifying records, undervaluing imported steel and iron rods to skirt customs fees. The local newspapers had big features on the scandal.
I'd love to poke around this possible connection, but I'm not sure the best approach. I really don't know how to navigate UK records and resources. I'd be grateful for any help and direction.