Thank you for this. Got it working using the information in that post.
For anyone coming across this post below are the steps:
Because I needed the sort order to be acsending (time) for one value and descending for the other (Ouput) I needed to invert one value. I did this by creating a new column equal to my time column but made the format “Number” not time and called it “Time Inverted”
I then multiplied the new time number by -1 to invert the values.
Made another new column with he formula If([Selection Choice] = “A”, [Time Inverted], [Output]. This formula would populate the entire column with either the time or the output depending on which Choice was selected. I called this column Time/Output
Then simply added a sort to my table based on the Time/Ouput column. And because the time is inverted the sort ascended on time, and descended on Output.