I am doing some of these just now and I am doing the two versions.
The paints I will be using are Humbrol 89 Matt Middle blue and Revell 52 gloss.
The curtain sided wagons would be pale blue body and Revell 52 for the curtain.
Put the transfers on the curtain which will sit better on the gloss paint.
The metal sided wagons will be done with light grey and 89 blue.
You can weather them with some light grey and light brown.
Seal the transfers with varnish before weathering.