Flywheel starter sprocket

Now I have a starter mechanism, my worries have turned to how it engages with the flywheel.
Those ratchet teeth surely cant be the genuine article can they?  Why is it made of two plates (one on top of the other)?  The two plates are riveted onto the flywheel and have clearly had a good old bashing at some stage.  Not only are the teeth damaged but the whole assembly has been knocked off center.

The scribed lines in the photo are concentric with the crankshaft and illustrate just how far off center the plates are.  You can see also that the plates don't even align with each other!

I think I am pretty well committed to getting this bike back on the road now, so for a little light relief this evening I decided to drill those rivets out and remove the knackered ratchet sprocket in order to measure up and make new.

The two sprocket plates (I'm not sure what to call these fellows) appear to be more than a home made bodge - perhaps they are as fitted at the factory?

I could if I wanted simply turn these plates over, swap their order and rivet them back as is - the backsides arent too damaged and I am sure it would be "good enough" and certainly "better".  Perhaps this was the original design intention? to be able to make good when they wore out?

Im not going to do this however.  I think I will make a new single sprocket out of solid 7.5mm steel plate

So I think I have a solution for this bit.
BUT I am still confused about the fitting of the flywheel to the crankshaft.
The flywheel has a keyway in it, but the crankshaft doesn't.
Of course the alignment of the flywheel (with its integral breaker points cam) and crankshaft position needs to be accurate and secure in order to create the spark at exactly the right time so I am surprised there is no keyway dowl.
There is however an odd 'spot' on the crankshaft.  Look closer and its a little hole - but no deeper than maybe a millimeter.  I wondered if this might be a hole for a location pin (that in this case has sheered off)...... or am I just fantasizing?  maybe its just pitting?

Looking at the exploded diagram for the engine, I am none the wiser.