My friend is a professional aluminium welder so it came to my mind if we should give a try to weld the cracks.
Is it at all worth to try?

I may of course send this one to you, but mail already costs quite a bit from Finland to US and back. And takes at least a couple of weeks...
But if you may have suitable and favourable used/new crankcases, I'll mail this broken one to you ofcourse.