The No1 enfield was never designed to take a rear aperture sight. The front sight bases were pinned onto the barrel on both No4s and No1s. For a front sight it would be easiest to have a gunsmith soder on a sporting front sight base. For a rear sight, it'd be best to probably drill into the side...
This is no run of the mill Winchester. Most places aren't going to have the correct parts to unsporterize a Russian contract Winchester 1895 in 7.62x54R because they are rare here in the US and most of the parts are proprietary. Good luck. Still awesome though that you inherited one of those...
The ballistol will dissolve into the water and pretty much turn into milk. Plus when you take all the parts out of the ultrasonic they will have a thin layer of ballistol on them too