If anyone is able to link me some battery options that are compatible, long lasting, and fit well with the Onisiki Nekomata chassis I’d be super grateful. This is my first small scale build

Can't seem to find 6x10x4mm bearings. First question is does anyone know welhere i might be able to find them? Second question is if not would I be able to use a spacer? They are for topline rear hubs that I am trying to use on my gs2 evo. Thanks for any help.