As far as level choices go, it’s really going to depend on which level you have yhe time to consistently complete the program. Either one will prepare you well for the race.
I’m more concerned about your projected time line for that sub 3:30 marathon goal. You gave a race time from October that was 16:55/mile. Your equivocal marathon pace would be around 14:33/mile. To hit a sub 3:30 you would need around a 8:00/mile pace. That’s over 3 min/mile faster than your current predicted mile pace. I’m concerned that if your goal is to reach a sub 3:30 marathon in the very near future you will either be disappointed or worse, injured. I’d personally recommend a sub 6 hour goal time for an immediate marathon goal and look at a sub 3:30 as a 3-5 year goal minimum.
Since you will definitely need to work on speed and then endurance, I’d step back and focus on the 5k/10K and then work up to the ½ Marathon. If looking for a sub 3:30 marathon you need to be in shape to run a 21:30 5K and a 1:39ish half. I’d focus on no more than 1 full or half a year as a benchmark race and work on 5K/10K ik between.
In addition, I’d recommend focusing on proper nutrition and strength training.
Gerald
80/20 Certified Coach.