I don't know if your status will get you out of the $75 change fee, but assuming there is no fare difference from the flight that you are on and the flights before and after- you ought to be able to change without much of a problem. If you want to change this itinerary as much as it appears that you do, the $75 change fee will be inconsequential.

Also, I am not quite clear: Are you planning on upgrading with miles, or status. If you are upgrading with miles, do it. If you are planning on upgrading with status, that is a riskier proposition considering the route in question. If this is the case, the $75 turns into a gamble. It is your call whether you roll the dice.