Yes, it is a VS2. I suppose that it could be a VS3, but it doesn't look like a 3/4 machine to me. The 27s and 28s started about 1890 and the 127s and 128s about 1912. The VS2 and VS3 wouldn't have originally been electrified. From my understanding many of the machines to which the motor was added were also "updated" with a new coat of paint, some with flat paint and some with crinkle.
You can read about the Singer vibrating shuttle machines
here. I take issue with the fact that they say the 27-4 machines are the hand crank models. They may have been for machines made in Kilbowie, but the ones made in USA were treadles.
For some information about machines which were 'electrified' can be found
here and
here.
Janey - Neat people never make the exciting discoveries I do.