strategic advice for the 1000

Anybody have advice on how to swim the 1000 free when you are in less than optimum shape? In past years, I worked out enough to feel I could just swim it by feel--i.e., go as fast as I could without bumping up against the lactic acid tipping point. I also swam the hour swim and a 1650, so I had some sense of how to pace the 1000. This year, my weekly workouts have been down by about 30 percent in total yards, and probably a similar amount in intensity. I have, in short, no idea how to make the best of a bad situation and am hoping somebody out there can advise! thanks in advance...