All Model 1917 receivers were nickel steel and none had "bad heat treats" as is commonly understood to have happened on "low number" Model 1903 rifles. However, Eddystone installed barrels by machine and some were overtightened. This has resulted in some (rare) seasoning cracks and (more often) cracks when trying to remove the barrels. The latter problem can be eliminated by relieving the barrel tension with a lathe cut just ahead of the receiver. No problem, as you are obviously not going to preserve the barrel.
The only 1917's available are seen at gun shows. They are mostly WWII rebuilds, but again this is of no concern to you. Prices have been running around $200-300, though sometimes one can be found cheaper.
Many thousands of those rifles have been "sporterized" over the years, and you might check local gun shops or put an ad on the buy/sell forum here. Depending on what you want to do, one of those might save you time and money, as the "ears" might already have been removed, the receiver drilled and tapped, etc.
I am not sure a Pattern 14 will work for you, as IIRC, the mag is not long enough for the .416, but I am not positive.