Honda-SOHC

I know Chris lives up your way Ash, he's a very good customer of mine and has been buying parts from me regularly for quite a few years now.

You could use them to put up some virtual shelves for ornaments that don't need to be bought Ted 

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Very interesting within Honda, is that they've built so so many different types in configuration and application, all good to compare design traits etc.

The three mentioned above all allmin the same area in regard to bhp per cylinder, more importantly loading (torque)  and speed all being close to specify a bearing for use in.

The detail in your thread about prototype 750, the small original big ends suggest it either started as a roller bearing crank or sized upward 8f origin in plain bearing, to control crank twist perhaps. 
Around that time were the car engine 4 cylinder too, with roller bearing crankshaft.

Yes, you'd definitely need a "depth" hardened surface to run rollers or balls on, thats in comparison to plain bearing arrangement.

That would mean you could regrind a crank, does anybody know if the journals are hardened cos i dont

If needing treatment after grind, process like this available https://aalberts-st-heat.co.uk/tufftride-qpq#:~:text=The%20Tufftride%C2%AE%20process%20of,the%20characteristic%20black%20surface%20finish. Suitable for materials that can't accept nitride treatment.