I missed the other thread, but recognised the parts immediately. If the parts are original I would see it slightly later. I used the earlier Benelux (bendylux)gears in 1950 with their not too good handlebar controls and could always change both at once off the saddle up hill. By a bit of bending I could make then do 6 speed. Also adjustment by bending helped to get the extreme gears. Wet weather would get to them a bit, and could be damaged by hitting the road, but the accuracy of gear change was far superior to the early Campagnolo GS.
Weinmann Alesa alloy 27 x 1 1/4 rims were the standard for general use at 18 ounces each, but always had a problem with the near vertical spokes on the gear side.
I used to get frames with Nervex crowns like the chrome one in the picture, and built to spec for the same price, sliver brazed as well. Mostly they made standard Moth frames, which yours looks like.
Keith