63 to 320
Don't do this, please. Enlarge it to 315 instead, that is the correct resolution.
Allow me to show what the difference is when you multiply the resolution which is the correct way, and when you pick a random resolution which is the wrong way.
This is an image of Reginald that was originally 50x50 and was enlarged to 250x250. Looks good.
This is an image of Reginald that was originally 50x50 and was enlarged to 270x270. Looks really strange on some parts(eyes, left leg).
Even though this isn't too noticable it's still better to do it the correct way.