At 100% on the screen, you will be able to see a 1px blur. At 300 dpi, you won't be to able to see such detail without a loupe. So if it looks detailed enough at 100% on the screen, it will look detailed enough in the print.
If you are looking for general information about image sharpening for print, take a look at articles and books by Jeff Schewe. One, with several interesting links is available here: http://www.pixelgenius.com/tips/schewe-sharpening.pdf