Every runner is different, the reason I am replying is because your 5k and 10k PR’s are almost the same as mine and I was able to run sub 5:30 pace for a Marathon. I am more of a strength runner rather than a speed based runner. My PR’s are 15:18, 31:51, 1:09:35, 2:23:52.
Here is a typical week of training for the Marathon:
Monday- 8-10 miles easy on golf course, Tuesday- 2 mile warm up, 7 miles at 5:30 pace on bike path, 2 mile cool down, Wednesday- 15 miles easy on dirt trails, Thursday- 8-10 miles easy on grass fields, Friday- 2 mile warm up, 5 X 1 mile @ ~5:10 pace, 400m recovery, 2 mile cool down, Saturday – 10 miles easy on dirt trails, Sunday- 20-23 miles on road, first half at 7:00 pace, second half accelerate to ~5:40 pace by the last three miles. I have a job, so I can only run once per day, and usually around 85 miles per week.