Hey Lurch, since you bought that Mazda from me, and you know I basically have a Mazda junkyard, and you know I can answer any damn question you've got about Mazdas, why not just send me a text?
As DAWGPIMP said, the Navi pattern is 4.7 mm larger than the Mazda. There is enough space to fit the wheel studs in the holes, but the lugnuts ride on the outside of the stud holes on the wheels. Not very safe in my opinion. It also puts stress on the studs, which in time will fail. Anyone that argues is wrong. I know that's a bold statement, but I had a wheel come off going down the interstate because the studs sheered off. My hubs and axles are redrilled to 6 x 135mm. So they fit the wheels perfectly.
Montero wheels? All the ones I've seen are 6 on 5.5, newer ones
http://cgi.ebay.com/ebaymotors/16-CHROME-MITSUBISHI-MONTERO-WHEELS-RIMS_W0QQcmdZViewItemQQcategoryZ42614QQitemZ8036499446QQrdZ1#ebayphotohosting
yes, they will fit, they are 6 on 5.5
these are also 6 on 5.5, those are older ones
http://cgi.ebay.com/ebaymotors/16-00-01-02-Mitsubishi-Montero-OEM-Alloy-Wheels-Rims_W0QQcmdZViewItemQQcategoryZ43956QQitemZ8034782410QQrdZ1
As for other wheels, I've been through this with you before. Z71s, newer suburban wheels are kinda cool, all the variations of those, Navis will fit (ghetto), escalades, old Pathfinders, the ones i mentioned to you before that no one uses: new Xtreme Colorado wheels are 18s and 6 on 5.5, 20s in a SS Silverado wheel
Like I said, there are all kinds of wheels, keep in mind they don't all tuck well, those Montero wheels are probably a prime example of that