The Leupold Custom Shop can do the Duplex to Mil Dot Conversion. Even better is the newer TMR Reticle. It is in Mil's only Dashes instead of Dots. I have had the TMR Reticle installed in the last 3 MK4 M1 16X scopes that I have sent in. They can also do the Target Turrets. You will need to call the Leupold Custom Shop and talk with them about price and delivery. Ask about the allen screws in the 1" Target Knobs. If they still have the Very Little Allen Screws in them, you should ask for a couple extra screws and a couple extra allen wrenches for them. Unless Leupold has changed the allen screws on the 1" tube scopes they are very small and round out if you are not very careful. You use the allen screws I am refering to to take the Scope Knob to Zero after you Zero your rifle. As the Zero changes around you will adjust the knobs back to Zero by loosening the allen screws, turning the knobs back to Zero, then retightening them back down. I have not seen a new 1" tube target scope in a while, hopefully they have started using larget allen screws, they needed to.
Leupold will fix you right up, and the price is not bad either.