What do you mean "is he going to be ok with our bigger girls?" What are your goals?. What do you want to happen? And most important what are your specific concerns? I find it easier to respond to specific questions instead of general questions. That way I can better answer what is really bothering you instead of having to guess.
You said he has hit puberty. How old is he? Is he trying to mate the hens? How are the girls reacting to that, if he is trying to mate? Are the girls mature hens or are they also immature pullets?
Again, how old is your Orp? Is he also an immature cockerel? Lots of different things can happen here. They will know which one is dominant. As one or both mature they may challenge each other for dominance. That could lead to a fight to the death or they may work out a way where they work together to protect the flock.
With any of this, the more room you have the better. Crowding them often brings out the worst behaviors but with room to separate things are more likely to work out.
Chickens can change personalities as they go through puberty. That applies more to males than the girls but don't discount the importance of how the girls behave to overall peace of the flock. Even if you answer all of my questions I still will not be able to tell you what will happen. There are all kinds of possibilities. Just give them as much room as you can and observe. Have a Plan B in case you need to separate one of them on short notice.
Good luck!