I was quite a bit faster than you at 5k when I tackled the marathon, and I limped home in 2:46.
Whether your 10k training will transfer depends on what your 10k training looks like. You need a lot of mileage and you need lots of miles at marathon pace. Build up your mileage and your long run first, while making your workouts mostly progressions to LT, long hill climbs (on the treadmill), and a few very fast fartleks with adequate recovery so you don't accumulate too much oxygen debt. Then transition towards making your hardest workouts all MP runs. Work MP into your long runs, and also add medium MP runs during the week. Touch on your faster paced stuff just enough to avoid total loss of speed. Recover less than you would when training for track. You need to ride the edge of overtraining a bit. Feel like a walking zombie for a few weeks before backing off, then do it again.
One trick for fall marathon training: Because heat accumulation can be a problem, consider doing MP repeats. Try 4x3 miles at MP with a few minutes in the shade pouring water over yourself in between reps. This allows you to get in the total volume you need without crashing because you can't shed all the extra heat (which you likely won't have to worry about in the fall when your race rolls around).
I'd aim for 2:40 first time out. Good luck and have fun. The marathon is a great equalizer.There are a million guys who ran 15:10 in college and never ran faster than 2:38 for the big one. But if you put in the work over a couple of years, you can be comparatively much, much more competitive than you ever were on the track.