Both cards have power/toughness setting effects. But Bell Borca's comes from a characteristic defining ability and thus is applied first, regardless of timestamp. So as soon as both cards are on the field, Bell Borca is a 3/3. The changing noted values don't change that, the new value is always overwriten right away by the Archon.
Former Rules Advisor
"Everything's better with pirates." - Lodge
(The Gamers: Dorkness Rising)
"Any sufficiently analyzed magic is indistinguishable from science."
(Girl Genius - Fairy Tale Theater Break - Cinderella, end of volume 8)