I had acl reconstruction a few years ago and was running 10k's before surgery then stepped up to half and a full marathon afterwards.
I took 8 months for a full recovery but had to build up the miles very slowly and had a great physio would gave me lots of strengthening work to do which I still do every week.
I did 6 months training last year for my first marathon so that I could take it slower, building up my milage after 2 weeks instead of one and had a 4 week cycle were I trained for 3 weeks and reduced by milage and cross trained for one.
On the LSR I used biofreeze when it swelled (only badly once were I couldn't bend my knee at all for a few hours), used compression tights and lay down with my legs up against a wall for 10 minutes after a run to allow the swelling to drain.
Strengthening work is the key to marathon training especially after acl reconstruction. However, I think it would be a big ask for you to do a marathon but you know your body!