mkIII 850 crank

I recently purchacsed a lot of norton parts from a estate sale some have lables other do not... I am wondering if you can put a mk 3 crank into a 70's 750 case I'm trying to figure out all my options before I start building the bikes

Hi, the 850 MK3 crank is larger between cheeks comparing to the other one so you will not be able to close your cases....!
the difference is about 3mm (1.5 mm each side ), then the shaft end on the drive side side is longer (but that could be shorten).hope this help!

Ya wanna sell that there MKIII crank???

A MK3 crank in a pre MK3 case is nothing a lathe won't fix. You need to take .060" off of each side, and while your at it radius the output shafts (relieves the stresses). As for the LH shaft, it's just a matter of shortening it, I don't remember how much, and rethreading and cutting the keyway. I did mine a few years ago. The nice thing about the MK3 is it has an extra fixing bolt holding it together.