I now see where the confusion is here. You mentioned interval pace in your post but are using "1/4" mile reps as the distance. Daniels uses the term reps to work on economy and it is normally around mile pace which other posters have stated. You chose Interval or "I" pace of between 86 and 90 seconds per 400. But.... He also suggests that you run longer than 400 or up to 5 minutes at this pace with about the same length in time for recovery, or up to 5 minutes recovery if your interval took that long.
Many of the posters have given you rep or "R" pace for the workouts. The poster who gave you a range of paces for 400's I feel hit the nail on the head. He hit a range of systems which is best. He just did it using the distance you chose rather than one directly from Daniels book.
I don't have the book in front of me, but generally his paces for reps or "R" pace are 6 seconds faster than his Interval or "I" pace, and that is 6 seconds faster than his Threshold or "T" pace.
You stated your a 39:20 10k runner which would give you a T pace of about 96 seconds, or 90 seconds for "I" pace, or about 84 seconds for "R" pace. Like i said, don' have the book in front of me, but these should be approximately what is in the book if I recall correctly.
If I were you, I wouldn't do 400's at R pace but cap them at 300's which would be done in around 65 to 66 seconds. Similar to what another poster suggested of no longer than 1 minute. Ok.... 66 seconds for you. Just my 2 cents!