This is going to be a challenge. You have your work cut out for you. Will look to the possibility he arrived in 1900.
Look, if you contact your cousins and they don't want to deal with you...what have you lost? Chances are there is a family member somewhere that will talk with you and you never know what you will find out.
Speaking on the phone is good. Make sure you have something that will prime the pump. First they say they know nothing, then when you ask something specific...or give them something...it lights memory in their head and you will be surprised what they know they didn't think that knew. Give it a chance...you can only gain something...nothing is lost.
Besides, good opportunity to ask for copies of photo's. They can scan and e-mail you or take them to the copy store and just copy them or WalMart and get copies made and send them to you. Offer to pay.
Will continue to look.