Main bearing fitting

[kthree]

Hi all.
I'm new here and this is my first question, hope you can help.
I have a fully rebuilt Supersport motor that has a slow and very annoying oil leak from a so far unfindable source. The motor has only been run in the workshop and has no miles on it. There is evidence of a thrown chain and some dodgy welding repair so the cases are kind of suspect.
So I have sourced another set of Supersport (Black motor) cases in good condition and plan to swap all the new internals from the rebuilt motor into the new cases. My main question is do I need to measure and plastigauge all the main journals again or should the existing bearings slot right into the new cases?
In other words can I assume that all the cast cases all the same size and the bearing measurements are around crank shaft journal wear?

Any advice would be greatly appreciated.

Thanks

[Trigger]

Welcome to the mad world of the SOHC.

Your cases need to match to use the same shells. The marks are under the front lip and as a example will be BBABB.
If the cases have the same lettering, then it can be done. As long as every shell is transferred from the housing to the same housing 

[kthree]

Thanks for the reply. That all makes sense.
I've yet to pull the motor so will check those numbers when I do.
Fingers crossed.

Thanks

[kthree]

BBCEE - v - BBBBB

So does that mean the two B journals will be a match?
Thanks

[Trigger]

They are a match as, long as they go back in the same journal housing