Have you read this little tourist books published in 1940? It's not particularly big (101 pages) but it is chock full of all sorts of interesting information and, more importantly, pictures of various rikishi of the day. Unfortunately since it's aimed at tourist...um, in the '40s ;-) it doesn't identify them and I'm not knowledgeable enough to do so. Still it can usually be had for $20 - $30 U.S. dollars at used online dealers such as Alibris.