Are the birds adults? It can be harder free-ranging birds that are accustomed to growing up and free ranging somewhere else. It is easier to free-range peafowl that you have raised since peachicks, but you can still free-range adult peafowl. You need to keep them penned for a long time several months or maybe even a year possibly so they for sure know the area. If you let them go too soon they could leave and not come back.
My first pair of peafowl I got from the zoo that closed down and they free-ranged the zoo. My first pair was the opposite of yours the peacock was an India Blue and the peahen a black shoulder. I wanted to free-range them so I kept them penned for a month then let them out. They were fairly tame and would eat out of my hand. They stayed for about a month, then one day the peacock was gone. He ran away on or near Christmas day. The peahen was still around but soon she ran off too. We put up fliers and everything and finally we found the peahen in a backyard and caught her. The peacock was sighted by a few people but by the time we got to the different houses the peacock was already gone. We finally gave up on getting him back and since then I have been keeping all of my peafowl penned up. I tried free-ranging again last year but the birds kept pacing the pen wanting to come back in so I just let them back in.
Another thing I can think of is predators. A lot of people lose their free-range peahens to predators because when the peahen sits on her nest she can be vulnerable. If you have a dog that patrols your property that could be helpful.
I am sure you can free-range an adult pair it just might take some time beforehand keeping them penned and getting them tame if they aren't already. 300 acres sounds great for peafowl and I am sure they will have fun exploring.
Zazouse free-ranges a lot of peafowl so she can give you some good advise once she sees this topic. Others on here free-range too so hopefully you will get better answers since I haven't free-ranged much.
