They work fine! Forget the G0lden Orbs - the EverCool 715 & 725 copper coolers from nexfan.com will blow them away & are a way more perfect fit for the BP6. Their 70mmm fans will keep you a lot cooler too. $15-17
Add the $2 copper shim for an extra edge too. Be sure to have a good coolong scheme for the Northbridge chip too if you expect to reach the highest OC speeds.
Most Celeron-1 series chips all crash at some speed just over 600MHz. One recent post had made 642MHz with air cooling & I think you should consider this a great acheivement if you can match it.