Hello,
I think they would be fine outside in the coop as long as they could snuggle up together. I would however be sure to lock them up in the coop at night for a week or so, or until they start roosting in there on their own. Being it would be their first time outside they probably would not immediately recognize the coop as home and might not roost in the coop out of the weather. They would likely roost outside in the run and be exposed to a cold wind or rain, which at this age could potentially kill them or at least be a health risk.
If you are concerned about it being too cold in the coop you could put a lamp in there for them. Since you've had a lamp on them for the first 6 weeks they should already know to get close to a lamp if they are cold.
Also if you have some low roosts installed inside the coop that might encourage them to roost in the coop. Chickens naturally try to roost up high at night. Yours might be a little too young for this instinct to have kicked in yet, but it will soon if not already.
Best of luck to you!!