Getting in distance swimming shape

Hi all -- I just joined this forum, and have enjoyed reading through many of the archived messages. Here's my situation: I was a decent distance swimmer in high school (e.g., 4:53 500 free) and am just now returning to swimming at age 34 after essentially 15 years out of the pool. After being back for about a month, my stroke feels OK and I crank out a reasonably fast 100, and I'm starting to think I'd like to get back into good distance swimming shape. SC Nationals are here in Phoenix next May, and I'd like to target the longer free events. However, I can't envision working out the way I did 15 years ago (i.e., double workouts, ~8000 yards/day). Finding the time for anything more than the typical ~3500M masters workout 4-5X/week would be challenging. Can anyone out there give me any insight into what sort of training national-level masters distance swimmers are doing? I'm interested in getting caught up on current distance training theories -- e.g., can interval training alone, without lots of yardage, be enough? I'd be very interested in any articles or other resources anyone could suggest on this topic. Also, a different issue I'll toss out there: I quit competitive swimming at age 18, somewhat before my potential prime, I think. At age 34, is it delusional to think I might eventually be able to go as fast or faster than I went then? Or are those days long past? I suspect people raise these kinds of issues periodically, and if I missed discussion of these points in the archives, my apologies. Any thoughts anyone can offer will be most welcomed. --Brad