did you mic up the journals to check the diameter before selecting your bearings?
While a highly worn crankshaft can be undersized. Oversized bearings are intended for worn out crankshaft journals that have been machined down to the next smallest size. usually in .010" increments. (ten thousandths of an inch). the oversize bearing takes up the difference.
Polishing with emery paper or similar abrasive typically won't reduce much material from the journal, usually it would be lucky to be .001"-.002" absolute tops. (one-two thousandths). It is very important to get your bearing clearances right or they will spin in their caps.
As you can imagine, If your bearing is oversize and your crank journal isn't undersize enough. you may have some serious problems with a bearing that is too tight.