No, found that number in on line white pages, not an old number.
Must have had a second wife. I found another entry to US under her name of Guadalupe Martinez de San Miguel that says under "who provided money" her husband Miguel San Miguel. This was in 1947. So before young Benjamin was 5 his parents had divorced, his mother had remarried and she was living in the US.
It's very possible that both "our" Benny and the mother remarried. In fact, I'm not doubting their marriage, but at this time I'm only seeing the "second" marriage for Guadalupe. Hmmm, I should be able to bring up an SSDI if she became a naturalized citizen.
Anyway, good job as you say we'll work this and see what else we can find.