Pretty respectable numbers, but still doing exercises on an aerobic end of what weights and sets should be to stimulate muscle growth. You'd have to quantify "old fart" for me, but I'm sure you could still pack on some good muscle mass by lowering your reps and increasing the weight you're lifting. For example, instead of doing 225 for 20 on your squats, do 275 for 8. Instead of supersetting your presses, do them as a stand alone exercise with 100 lbs for 10. Your body will adapt to the stimulus of higher intensity for shorter duration by putting on mass, provided you are eating enough protein and sleeping enough to recover. I like what I once heard Stan Efferding say: "Big muscles aren't built in the gym. They are built in the kitchen and the bedroom."