SK makes a none intrusive scope mount for the M1917 Enfields (Eddystone/ Remington/Winchester) . That means no drilling or tapping. Cost is $78 including SK rings. You can order a weaver type base but then you have to supply the Weaver rings and they can't be switched around.
I have one on order and will report how it works.
I have the SK model for a M1903 that works great (drawback you need a stock you don't mind cutting a bit for the front band to fit but you don't have to wreck the receiver value doing it)
I would urge anyone who has a M1917 Enfield that is of historical nature (well preserved with original barrel and receiver intact, i.e. not drilled and the ears on it) to not modify these.
They are truly historical guns now and should be kept intact if not already modified.