they will hold your ADR for 15 min. we've shown up later due to transportation issues and they still seated us. You would have to take the monorail to the TTC and then get off it and get on the Epcot monorail. Then enter the park, walk ALL the way to the back. So with the holding time, you have 1 hour. I think it's do-able, just make sure to hang out at the front of the park at MK so that at 7pm you are quickly leaving. Walk fast and you'll make it.