The lever always works the same direction.
This isn't true. Doubles custom built for southpaws with left swinging top levers aren't all that unusual. A while back I handled a nice pair of Dumoulin DRs, .470 and .375, built for a left handed shooter. A good friend, who is a southpaw, wanted them, but couldn't get past the left-swinging top levers.
Can't ever tell about cast from pix.
I wasn't relying on photos. The gun is stocked with cast-on.
Semi-beavertail are just fine for double rifles, maybe prefered, it's the extra pressure from the hand-hold that has been a problem with - mostly - shotguns restocked from splinter to beavertail. Beavertail increases control which is a definately a good factor for a rifle. I'm quite sure Holland has grown beyond the consideration of loop strength with their doubles.
None of this is true. Steven, rumour has it that you're a pretty sharp shotgun guy, but you have a lot to learn about double rifles.