Yeah, if you an run 1:20-1:25 and have reasonable training/pacing for your marathon, I would think sub-3 should be a reasonable goal. If you want to make sure you can get in for Boston I might even suggest shooting for 3:04:59 (beating your BQ by 5 minutes) to be safe.
So I saw some questions floating around regarding the qualifying process, and I know this is probably basic knowledge to some on here but I thought I would share some insight (as well as rumors/speculations regarding 2014)
Qualifying:
Time window - time must be run within about the last 18 months. So for example, the qualifying window for Boston 2014 started on 9/22/2012 and you can use any time after that date up until registration closes. My last marathon (that I finished) was actually run the date after the window opened, so I had serious thoughts about dropping out yesterday. I am fairly certain
Juxt has a qualifying time from 2012 Chicago marathon as well. (just not sure if he's planning on doing this again next year

)
Time Standards - The BAA site is down (or confusing) right now since they are still in semi-race-day-format. But I found the standards here.
http://runnersconnect.net/boston-marathon-qualifying/
Registration Process-
Registration opens in early/middle September. In the first 2 days you can only register if you have run 20+ minutes faster than your BQ. In the next 2 days they also let people who have run 10 or more minutes faster than your BQ register. On day 5 it's 5 minutes or better. Finally on days 8-12 anyone with a BQ can register.
However, you are not guaranteed an entry until you receive a confirmation e-mail. For the people who register during days 8-12, BAA will rank you based on how much you beat your standard by and assign remaining slots to those with the largest qualifying margins first. So they only have 1000 slots left and 2000 register, the 1000 people (regardless of when they registered during days 8-12) with the largest qualifying margin will be awarded the spots. Note, 38's not the fastest. (so a 18/M with a 3:03 will be ranked behind a 38/M with a 3:06)
For the 2012 marathon this cutoff was approximately 1:15-1:30 faster than the actual BQs posted. (so that year the men's 18-34 standard was still 3:10, but i think the cutoff was 3:08:4x for this group)
For the 2013 marathon there were actually spots left after the initial 2-week period, so they reopened registration in early October on a first-come first-serve basis. I think it filled 2 weeks later.
Based on some rumors I heard so far, due to the number of people who want to run next year to show support for the race, there's speculation that the situation may be more like in 2012 where just hitting your BQ may not get you in.
Registration Date-I am not sure if BAA has posted registration opening dates for 2014 yet, but as a point of reference I found my confirmation letter. (I registered about 5 minutes after it opened on day 1) and the e-mail was dated Monday 9/10, and I think registration opened on the 2nd Monday of September the year before as well.
Qualifying races-With that said, I pulled together a list of races within 2 months of the initial 2 week period. I am not sure if all these races are qualifiers. (I know the Equinox Marathon in Fairbanks is NOT, but that course is ridiculously difficult anyways).
http://www.marathonguide.com/races/races.cfm?Sort=RaceDate&Place=USA&StartDate=7/24/13