Now you know what a small journal crank looks like inside. As GB says, get that other plug out, the cavity behind it will also be well clogged up.
The plugs were never (or rarely) removed for the oilway to be cleaned out, back in the day. The crank grinder took your money, and in a matter of a few short weeks there was a good chance you would be back again for another grind. In the Service Sheet, 206, Engine Dismantling, it gets just two short sentences, a matter of four lines of print. Most owners, including me, looked at the plugs, reckoned they were in there for life, and just flushed it through with paraffin, little realising what was inside.
As it is a rare crank I would only have it ground if the journals are worn or scored. If still within size and not worn oval (there is a suggested 2 Thou ovality limit) you may get away with just a journal polish, which is the final stage in grinding a crank. Essential to ensure no sharp edge to the journal oil supply holes, a sharp edge will gouge a groove your new shells. Lots of information on the Glyco Bearings Website.
Same with the timing side journal. Only grind off the minimum to clean it up and go for a one piece custom bush, line bored to fit the crank.
Swarfy.