Specialized items like yours are really difficult to get a good price estimate. Alexander A and the Curator give you a pretty good benchmark for a 1917 Rifle's value and Winchesters really do bring a price bump while an Eddystone can be a bit lower than std. simply because of old stories about receiver cracking. But prices have been moving up consistently on old WWI warhorses that are complete--one reason is that complete stocks--regardless of condition are now bringing $200-300 as Boyds has quit listing its military replacement stocks for these (still have the sporters), complete military barrels depending on condition $150 or higher, and so forth. At the bottom end of condition and rarity, price is set by what the parts will bring.
From what I've seen, there are several sellers on Ebay and Gunbroker that do nothing but buy old rifles and break them up for parts. As I mentioned on another value thread, the low value of barrelled receivers in a particular rifle on Gunbroker tells you that a lot of rifles have recently been broken up for parts. The large parts houses are increasingly running dry on a lot of old milsurp parts--bulk buyers have been reselling their stuff on ebay and getting rifle parts cheap from other sources such as individual sellers is drying up etc.
To truly get the highest price on a specialized item--e.g. Canadian cadet usage and so forth, you really need to appeal to collectors who are specialists that have a gap in their collection. Online auctions are one place and others such as Gunbroker can be another but you will give back part of your money to them and some collectors are wary of dealing with a one off from a seller (at the high end counterfeits are a possibility). Another place would be a military arms gun show (there are a few around regionally) or a mega gun shot or some of the antique military dealers who might sell it on consignment. Another possibility but difficult if you are an outsider (same distrust as above) is to sell via the military surplus boards.
The THR is more a generalist board but places like milsurps.com or Gunboards.com are good places to determine what you have and what it might be worth--you may get an unsolicited offer from a board member through a PM after such a post. Be prepared to take very good and detailed pictures if you want top dollar from selling at a distance.