I've got a
3L MPV in my Cougar, so I might as well share a little info.
For a full 3L it is pretty decent, not a lot of work to do. The only Mazda specific pitfall I found is that the MPV injectors will not work with Taurus injectors maps, so unless you have a tuner with experience with MPV tuning you'll need to stick with either stock SVT or Taurus injectors. Also, if your engine doesn't come with studs in the motor mount then you'll have to track down studs from an 01+Cougar or from a Mazda parts department.
The oil pan is a direct bolt on to the MTX75, but the thin shim is slightly different, didn't measure the thickness when I had both next to each other, they seemed close, but the MPV has some more area's covered.
My MPV block came with block heater, not sure if it was just because it came from French Canadia (Quebec) or if that's standard. The MPV knock sensor bolts on to the block about on the back of the block. The rear roll resistor bracket looked very similar to the 2.5L bracket, but I'm not sure if our jack shaft will bolt to it or not.
The MPV LIM is the same as the ST220 and the Mazda 6. The UIM is very similar to the ST220, but has extra ribs in the castings and uses the IAC thru the TB like the plastic manifolds do. It also has a electric door that seperates the two plenums at the back of the manifold. I assume that it opens at high RPM for some reason I don't know yet.