I've seen posts claiming stuff was balanced to within a half gram... I've matched weights on pistons & rods... I've never balanced a crank.... I've bored & honed, decked & line honed... Doesn't change the fact I build cars that get driven a lot & get used hard... I don't see the point of chasing every last fraction of a horsepower... If I were building to that level I probably wouldn't be using 440 Source Crank kits.... For what the OP is building I'm confident 440 Sources balance job is fine & I would bolt it together & run it.. I would check bearing clearances, I would check ring gaps, I would clean & lube everything like I always do... I wouldn't get concerned about the balance... Sorry, it just isn't that critical for a street engine....