Check: gunboards.com (under buy/sell/trade)
check on: ebay.com under rifle stocks
your eddystone is usually referred to as the model 1917 eddystone in caliber 30/06. your rifle was made in 1918.....................................
made December 1917
300-750 dollars depending on the amount of original finish remaining on the rifle,and the stock and a good bore.
100-800 usd
Check with local gun shops
50-500
Weaver
By comparing the serial number to published charts. sales@countrygunsmith.net
Remington made 646,000 US model of 1917 rifles for the goverment during world war I. Winchester and eddystone also produced rifles for the U S goverment during that time,with eddystone being the largest producer.
S & K Scope Mounts in western PA makes one for the Eddystone http://www.scopemounts.com/ Look under "Insta Mounts"
John McGillen was born August 6, 1917, in Eddystone, PA, USA.
Good luck. You would have to search the National Archives and hope that the records exist.