B,
Congrats on your marathon PB! There are multiple great combinations to fill that gap, including the ones you’ve listed. The Maintenance plan was written for people who didn’t know what they wanted to do between plans. There’s actually nothing wrong with not knowing what you want to do between plans, you don’t need to train formally for 52 weeks a year. Some unplanned time is what the Maintenance plan is for.
Having said that, if you now you have a goal specific to speed, I’d instead consider the Run Faster plan (7 weeks, I think,…) then the 10K plan and then the Maintenance plan for a few weeks. Also, feel free to add in some one-week breaks between each plan. Run Faster, Break, 10K, Break, Maintenance, Marathon…
David