I am guessing that the 35 in the 1st example is the time they would go through 200 in and finish in 52.5, and therefore the 54 would be the time they go through 400 in and finish in 62.
This is pre-season work, 35 through the 200 and 52.5 @ 350 and 54 @ the 400 and 62 @ the 450, keep in mind this is for 46 1/4 milers, adjust to your ability. The 350 is a staple in his program, the times will come down, sometimes when in top shape, they will do 1 350 but @ race pace, or as MJ did before a meet, 2x 350m @ 46 with 3 minute recovery, he felt if this went well he was ready to do some damage. FYI, if you are really interested in Hart’s program, his 200/400 program on DVD is excellent, 3 hours of info.