That's very good. I found an article online that states that a drop of 45 beats means good fitness, so you're doing great! I believe that resting HR is also important but the more critical factor is the recovery heart rate (how much it drops after intense effort).
As for your resting HR, while 58 is higher than some cyclists (e.g. mine's 41), you're 64. They say the average heart rate (diregarding age) is about 70 bpm, although I don't believe that, i think it's closer to 80. So for a 64 yr old to be at 58, you're doing better than most 30 year olds. Also, I believe that the avg. resting HR of most endurance athletes is claimed to be around 50-60 bpm, so you're doing well.
Some of this is genetic and means very little for your fitness levels. For example, Santiago Perez (fromerly of Phonak) had the lowest measured resting HR of any pro cyclist at 31 bpm. That's even lower than Lance, yet who do you think has the better fitness levels?