If he can get at the needle bearing from the outside , he can use a socket , piece of pipe , thick washer or short piece of flat bar with a hole drilled in the centre that just fits inside the case bore but pushes only on the bearing outer ... then use another socket or piece of pipe and thick washer or drilled flat bar that clears the outer race on the inside and tighten a bolt and nut going thru everything ... That'll gently press the bearing out ... and he can put it into the new case using the same method ... Fitters have to improvise like that all the time since you can't take the job off site or take too long waiting around for specialised pullers and presses etc to show up ...
Another way to get tight bearings out (if he's going to chuck the broken case away) is to drill holes beside the bearing until it comes loose ...
It appears to me that he's not the type who'll take parts to shops for repair and wait ... otherwise he'd have stripped the engine and taken the broken case half to a machine shop to have it repaired ... A decent repairer could easily have machined the broken drain plug boss off and welded a new threaded bush on .. OR even fitted a threaded brass "Hat" bush thru from the inside out ...