Pappy Fiddle,
While Josh Sr.'s guitar did have a slotted peg-head and a 12 fret neck, it was not a classical guitar. His 1943 Martin 00-21 was X braced with a pin bridge and was made for steel strings.
Josh did own an Ovation Josh White model, but he preferred the Martin and seldom played the Ovation.

I never saw Josh Sr. live, but I did see Josh Jr. a few times during the Great Folk Scare of the Sixties, when he was still playing without a strap and with his right foot up on a chair so his guitar could rest on his lap, the way his dad did.

I was sorry to hear that Josh Jr. passed last week. RIP Josh.