The problem with scoping the 1917 is that each job of cutting off the "ears" was different. Gunsmiths just were not consistent when they hacksawed off those ears, filled the hole, and filed down the receiver (milling machine, what milling machine?). Using bases for the Model 30 Remington should be OK but be prepared to use a shim if needed. (The Model 30, 30S and 720 all used leftover Remington M1917 receivers and most other parts except stocks and non-.30 barrels.)
Jim