Hello and help with 1931 Japan Tour ball?

[Misha]

Firstly hello! I'm a collector of mainly modern GU items but joined here expressly to get the wisdom of vintage collectors.

I live in Japan, and recently on a Japanese online auction site (kinda like ebay) I came across a signed ball that has a total of 16 signatures on it, but the owner could only identify 1 which was Lou Gehrig.

Figuring it was possibly a tour of Japan ball I did some research and identified the following (grouped according to location on ball):

Lou Gehrig
Rabbit Maranville
Willie Kamm

J.E. Reardon (umpire)
Frank O'Doul
Muddy Ruel
George Kelly
unidentified (upside down under Kelly?)

Lefty Grove(ss)

Dr. Leonard Knowles (Team Trainer)
Ralph Shinners
Al Simmons
Herb Hunter

Larry French
Billy Cunningham
Tom Oliver

These match exactly to the 1931 Tour of Japan roster but is missing Mickey Cochrane (the upside down name seems to be Cochrane, but the first initial is a G or S?), and Frank Frisch to be complete.

Here are links to auctioned Tour of Japan balls I found and then my ball's photos. I would like to know everyone's opinion as to the authenticity of this ball. To my untrained eye, the signatures on my ball seem to match the flow etc of the ones in the auctions. Crossing my fingers!

Thanks for any info, Michelle

Previously auctioned balls for comparison:

http://www.lelands.com/auction/aucti...igned-Baseball

http://www.legendaryauctions.com/Lot...ventoryid=9082

http://sports.ha.com/c/item.zx?saleN...lotIdNo=405001

http://sports.ha.com/c/item.zx?saleN...&lotIdNo=24001

My ball: