I had the privilege of meeting Bob Wilke's grandson, Mark, last Friday. The company is now called Leader Paper (rather than Leader Card, who sponsored Watson's Indy cars). Mark is a customer of mine.
They're still in business, about 6 blocks from where I work, and I have been invited over to check out some of the memorabilia that remains at the shop, including a number of pictures of the Wilke Ferraris, some midget racing stuff (non-MG), and Indy trophys.
I've been told that they have film from every Indy race they competed in. A LOT of film.
It will be a few weeks before I can make the time, but I'm looking forward to it.