If timing went perfectly and everything goes smoothly, you'll still be cutting it pretty close. If your plane is delayed, passing through customs takes longer then expected, you have to wait for ME or your the last resort off of ME, there is unexpected traffic, etc. etc. etc. are all factors that are out of your hands. Sure taking a taxi from MCO to POFQ and then a taxi from POFQ to Poly can save you some time, but IMO it's still cutting it a little too close for my comfort zone.
If it's a restaurant you really have your hearts set on I'd push it off until later in your trip. No need to start off a Disney trip with the added stress of will you make it to your ADR in time or not, especially if your talking 'Ohana. If you are the slightest bit late to your ADR at 'Ohana, they can and often will skip your ADR and tell you to wait with the walk-ups. They are probably the strictest of the restaurants when it comes to ADR times, even for the first seating of the night.