RM 125 crankcase swap

[Nipper]

Is it allowable to use RM 125C crankcases on a RM 125B motor and still comply the bike as a pre 78 ? I have had a look at Alpha sports web site and the part numbers for the B and C crankcases are the same.
I am currently rebuilding a motor for a RM 125B and there is some damage to the cases , so i thought i would use the C cases, is this a no no ?

[crs-and-rms]

i bought a nos set of 125 b cases and they didnt have any serial numbers on them

[Doc]

Theoretically the C engine in it's entirety should be deemed a legal 'flow on' having no major changes when compared to the B. Emphasis on the word 'should'  

[Nipper]

Cheers Doc,maybe i will  just use them and beg forgiveness afterwards  wonder if that will be ok ?

[Doc]

sounds okay by me..but then so do lots of things that don't conform nothing a file wouldn't fix

[Nipper]

Mmmm , I do some of my best work with a file.