As long as the pullets are very young they should be ok but if they were older and street wise they would chase the rabbits who are pretty placid sort of creatures generally
Trouble with chickens I always found was as they die 3/4 years if your Lucky you can't introduce younger chickens to the pen as then there is world war three so best to replace them all together
Feeding time could be an issue though as rabbits tend to nibble all day and hens will steal teir food constantly