16 weeks to train... but for what goal?

crux

Ok, I have 16 weeks until I start a muscle building phase in the gym at which point I’ll be cutting down my cardio to a maintenance level.

I’m looking for a running/cardio goal/training plan to be completed within these 16 weeks… but what should it be… I’m unsure what to aim for next?

I can already run and I do three days per week outside of lifting. A 4-5 mile tempo run, a day of Interval training, and then a 10k+ each Sunday. My tempo runs are at 8 minute mile pace.

I’m just a bit stalled now with my running. So what would you do with 16 weeks…

1) Train to run a fast 10k
2) Train to do a half marathon
3) Or go the whole hog and try a full marathon (can that even be done in 16 weeks from where I am?)
4) Other

Looking forward to hearing people’s views and suggestions.