All good replies, but I want to reiterate that I'm not looking for firm WOT up shifts. I'm just looking to increase the shift point in my Mercury's stock AOD.
Remember, this car is currently equipped with the lower performance version with the old 289/302 firing order. It makes the same amount of torque as the 5.0 HO, but it comes on 1000 RPM earlier. Hence, earlier shifts. If I put what is essentially a Mustang 5.0 under the hood, these earlier shifts are going to make the car gutless on every upshift.
I drive this car mostly on the highway. The primary reason I'm doing this is to get more higher end power for better passing and what not. But I'll the higher shift points for whenever I'm city driving or accelerating on the highway. As it currently sits, the car shifts into overdrive at 41 MPH! Plenty of off the line torque, but it fall flat anywhere above 4000 RPM.
Installing a governor from a Mustang was actually a fairly common swap in the Panther platform community until they were discontinued.