I would not replace the crankcase for that; a succesful replacement takes much more than a new part.
You will need special tools, new gaskets and heating and cooling in order to transfer everything over.
Although it is difficult to asses the damage to the bearing casing from the pics, it is all about the amount of aluminum area hugging the bearing.
That is called an interference fit, which means the diameter of the aluminum housing is smaller than the diameter of the bearing and the assembly is performed with the bearing being cooled down and the casing being heated up.
If the remaining area is above 80% of the original, I would say the bearing will stay in place without spinning or shifting.
I woud tap the shaft and the outer ring of the bearing all the way in, as far as they can go.
Then, carefully assembling the clutch, checking free rotation and proper meshing of the gears for each step and applying the proper torque.
Also, verifing that the transmission and shifting works flawlessly and silently.
Clean the old gasket from both surfaces, caring not to dent or scratch the soft surfaces, apply grease over both sides of the new gasket, set it in place and bolt the cover in a cross pattern.
Replace oil and go happily riding for many more miles.
You are welcome.
