RARE? What makes you think that they are rare? Is it because you have one and you think that no one else has one? I have one also, does that make mine more rare than yours because I am in the U.S.? PLEASE DEFINE RARE.
All those who think that they have something that is rare and have never bothered to find out for sure, and then think that they can get 'lots' for it because they decided that it is, you all make me sick.
QUIT TRYING TO RIP US ALL OFF.

Perhaps I should have clearer, E1 as in the old 1200cc pushrod engine that the J series was based on.
Hope this helps.

NO Not even, cap, rotor, points, and other things will interchange, but the main body will only work on the old E series and J series engines.

Why not just buy new ones from Nissan? Part number should be 44200-18000

Check your valve adjustment. It's possible that the clearances on you # 4 cylinder are too tight, causing one or both valves to be slightly open until it warms up.

Is there something stuck between the needle and seat, or is the float out of adjustment?
Another possibility is that your fuel pressure is too high and is forcing fuel into the carb.

try H190, possably out of a 410/411 wagon or a 510 wagon. B24 would be a casting mark for a 520/521 pickup, which also used the H190 diff.

Changing to flat top pistons won't gain you that much. Te biggest bang you'll get for your money should be in head mods, ie; a good port job, an increase in intake valve size, along with larger inside diamiter seats. Then, maybe consider changing to a hotter cam, increased carburation, and headers (extracters). Unless there is a reason to keep an A12, why not just install an A14 with the same mods? You get a whole lot more in the same size package.
Basicly put, make it possable for the engine to breathe, 40 DCOE's work much better when the engine can get air/fuel in and out and a stock head isn't capable of handling that much more than the factory provided. Open up the ports and the valve area and things start to work the way you want them to. Why else do you think that GX heads have big oval intake ports instead of the small round ones?
As far as compitition oil pumps go, pressure doesn't help without volume. All of the factory compition oil pumps that I've seen are high pressure with the same rotor set as the standard pumps. If you really want to increase pressure, increase the volume and the pressure will also increase at the same time due to putting more oil through the same area. It is possable to adapt L series rotors to an A series pump with some machine work and a spacer, there have been posts about this in the past.

The chaging system is fused through the fuse box, if blown it will cause dash lights.
Also, has the alternator been changed recently?, I know that it's a remote possability,
but I have seen where an external regulator alternator was replaced with an intenal regulator unit. Easy mistake to make as they do look very similar.

It could also be as simple as a blown fuse.