That’s awesome! We all slow down as we age up, but the key to not slowing too fast is to train right (80/20)…get good sleep and eat right. Sounds like you are on the right path to achieving your goals!
I am six month ahead of you and on full speed ahead, training for half marathons and 70.3 triathlons in 2022. I do get occasional nerve pain in my femur when it gets really cold and the clunkiness you mention is a constant work in progress….not sure if it is age or surgery:-)
Good luck and keep us posted on your progress.