I studied the pic for some time but can't blow it up enough to be certain about that blade. It looks tapered towards the top, but when I stare at the lower part, it seems parallel. A parallel blade makes more sense in a lever-capped as opposed to a wedged plane, it makes adjustment a lot easier!
There is something about the lines of the front end of this plane that make me think it's not from any of the major makers whose work I've seen, and the placing of the pivot for the lever cap so high on the central "hump" is a bit odd. I agree with the view it's a home-finished casting, and quite well done.
There must be quite a few user-made planes from one-off or small batch castings made when there were lots of small foundries around. The quality of finish on the few I've seen varies widely. I picked up this 'shell' from a junk-store a few years ago (after talking the seller into a price that was more consistent with the quality & state of the piece!)
That is all there was to carry home, I had to make a lever-cap & find a blade. The woodwork was too roughly-fitted to bother trying to fix, so I made new infill from some spalted Casuarina I happened to have (it has a grain pattern a bit like Beech, but the rays are a bit larger).
Turned out a decent general-purpose user, able to give a good account of itself on moderately challenging wood:
But the casting is pretty rough & ready and I could never get thet mouth cleaned up without creating a huge gap, so I left it alone. The cap-iron wil have to do all the work on this one:
Cheers,
Ian