Yes the babies will need access to heat but with your temperatures, they can be off heat completely at around 3 weeks.
Do you have electricity to your coop or run? I brood outdoors, in sight of the adults, to make for a more "natural" integration. It sounds like you have sufficient space to do that easily, if you set up for it.
My article on early integration, with several others linked at the bottom: https://www.backyardchickens.com/articles/short-on-time-recycle-a-prefab-brooder.73985/
Do you have electricity to your coop or run? I brood outdoors, in sight of the adults, to make for a more "natural" integration. It sounds like you have sufficient space to do that easily, if you set up for it.
My article on early integration, with several others linked at the bottom: https://www.backyardchickens.com/articles/short-on-time-recycle-a-prefab-brooder.73985/