Welcome to the site.
I would first consider a spare
ball unless you can throw those
balls dead straight at your spares with no effort. If you have never been to the Nats before then you will not be able to hook the
ball at your spares with much success, the lanes are oiled in a sport pattern and there is no river of oil in the middle of the lane to hold errant shots on line. I have seen 230+ average bowlers hook the
ball at spares and the
ball either not hook a board or snap off into the gutter.
That being said I would go with the first 4
balls, dull the No Mercy to 1000 and the
Cell to 2000, the fury 4000 and shined, the absolute with rough buff, they can prep the
balls for you there at the nats
Pro Shop area, if you get there the day before.
You might also get info out of my other post on this subject:
http://www.bowlingcommunity.com/b/ubbthreads.php/ubb/showflat/Number/49927#Post49927