I am not sure I understand why you want to do this.
If you have a "native" population of pheasants it is most likely close to the maximum the area will support. Either the wild feed, cover or predators are limiting the number in your area.
When I was under 10 we had lots of pheasants in our area. That was in the late 50's and early 60's. Since that time we have none. We tried several times to "establish" pheasants in the area. Many neighbors tried together each releasing hundreds each.
Everytime it has failed. The area has changed. Windbreaks were removed, crops became less diversified. Predators adapted to the changing of farm to near suburban land.
I have no idea where you are, however, I think you should rethink the whole plan. If you really want to try it go for it. But go for it with your eyes wides open and knowing it will most likely fail.
Pheasants were an introduced species and are not native to the USA. They have failed to adapt to the changing landscape. Even South Dakota releases millions of pheasant each year to the wild to keep people thinking it is the pheasant capital. Without those releases they would die out there too.
Good luck, sorry to be a pessimist on this.