I will bet that the changes in drive train were significant enough to let the body sag until the subframe connectors came into play. The latch is pushing down on the strike and even though you release it, the bind is such that the latch isn't releasing from the strike. Once you get it open, take the strike out, realign the door, which will be too low in the back and then replace and adjust the strike. the question is how to get the load off the strike. If you really can't get it to let go pulling up on the handle (or maybe the inside frame if you get the inner panel out), I have been successful taking the rear quarter inner panel off, grabbing the threads of the strike and screwing it in (toward the door). Once loose, the strike will move and relieve the pressure. One more try would be to try jacking the car up in the middle to relieve the pressure.
