here ya go.... I am just learning about National now myself. I got a slightly later model recently and have been working on gathering info.
Neat factoid: National had a lot of product lines and brand names that they marketed under. in 1962 they sold their most famous, the "True Value" brand
Qeneral info about National
http://www.ismacs.net/national/home.html
This ad looks similar to yours.
http://www.ismacs.net/national/eldre...rtisement.html
The bottom portion of this page has some info about National...
http://www.sewalot.com/willcox_gibbs.htm