Erik is giving some pretty darned good advice, here!
I will give my "thought" such as it is...
If you are baking a potato or potato's that big, its going to take an hour in the oven, at 400 degrees, perhaps slightly hotter if you are using an electric oven, on "bake" function...ie the potato's on the lowest rack, and the heat coming from the bottom...in a perfect world, turn them over with tongs, halfway through...
We are going to want to broil the steaks, given the 3/4" thickness, on a broiling pan, on a rack at the very top of the oven...(so make sure you have your oven racks set up right when you "start" the potato's!)
Coincidentally, 21 days aging is what I would call "minimal"...you might want to abandon the "dry rub" method, and try this instead...
Mix a third cup of EVOO, with 2 tbspns of minced garlic, a dash of hot sauce, a tbspn of Worcestshire, and a quarter cup of mesquite BBQ sauce together, and flop your steak in through that, both sides, allowing it to marinate while the potato (s) cook...flipping it when you turn the spuds...
(This works so well on a BBQ, too!)
Remove your potato's and set aside...
Preheat broiling element (max out the temp!) to fully red and pop in your steak(s) on the grilling pan...for medium rare, cook precisely five minutes, and then "flip" them...cook another five minutes, then remove the steaks and pan, and allow to "rest" for five minutes...drizzle with the drippings...and serve...
(Mind, Erik is perfectly correct in punching the meat with your thumb to test "doneness") I prefer the meat being "salted" with Hy's Seasoning Salt, either immediately before, or immediately after cooking, presently, my vote is for "after"...if you cannot access "Hy's", try Kosher Salt and fresh ground pepper with a bit of paprika...
One final point...I believe the meat should be allowed to reach "room temperature" or so before being offered up to the grill...its hard to evenly cook and unevenly thawed piece of meat...even if that meat is only "chilled"...
I stand to be corrected by the pro's on line here...but this is more or less "my method"...
Lifter