I'm not sure what world Nu-Cast were operating in when they decided that the whitemetal loco chassis would provide adequate bearing surfaces, but in my world they were wrong.
With all those waggly bits hanging on the outside, I really don't want to have to strip the mechanicals down just because after a prolonged period of running, the axle holes are the shape of a Wheetabix rather than round.
So, after digging four brass bearings out of the pot you saw yesterday, I reamed out the holes in the alloy lump and glued the metal bits in place. Reaming took rather longer than I expected as the hole enlargement is greater than I expected but once done and with the holes countersunk, the bearings were pushed in to place and then pressed home in a vice. Only one needed a smear of runny superglue too.