The misalignment isn't difficult to correct, and I've seen it on a couple of other older engines of various manufacture.
I'd like to recommend that you use a sharp round file to open up the bearing hole in order to match up the passages. Then carefully chamfer it with sandpaper like the crank holes. The reason behind this is due to the possibility of oil pressure literally pushing on the back of the bearing. If there is enough bearing area sticking out into the hole misalignment, and the oil pressure is high enough, there can be problems with premature wear on that part of the bearing face around the hole.
Even though it may not look like much area hanging out over the hole, the net effect from the physics of "pressure times area equals force" is no different than if a small piece of crud (metal, dirt, etc.) is left between the bearing shell and the block when you assemble the parts. It will create pressure where it's not supposed to be and result in excess friction.
The only apparent issue with this method is the "large" hole, and the apparent lack of support for the crank due to the missing shell material. But that "hole" is filled with pressurized oil when it's running, and the crank is supported on the hydraulic pressure, instead of the pressure pushing on the backside of the bearing and squishing the oil film down too thin on the crank side.
I hope this helps out, too.
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David
newbie #4153
