Interestingly enough, I'm also 63, 5' 10" and about 210 lbs. I have been lifting longer than you have, since I was 54, so there is that difference between us. I got myself fairly strong over the years, with a 525+ deadlift, 430+ squat and 250+ bench. After I got myself to those numbers, I starting feeling kinda beat up, especially in the lower back. I took some time off (a month or so) completely and started back with very conservative weights with very little progression. This got boring after a while so I decided to go back to a modified NLP. Nowadays I rarely lift more than twice a week and never stress my back with squats and deads in the same workout. Monday is squat day when I do 2 heavy triples and one back-off set of 5 at about 90-85% of the top set. I then bench a standard 3x5 and finish with a few sets of weighted chins. Wednesday or Thursday is press and deadlift day. Press is standard 3x5 and deadlift, like the squat, is two heavy triples, but no back-off, ending the workout with some HIIT. If I can fit in a Saturday workout, I squat the back-off weight I did that week for 2-3X5, plus whatever accessory I feel like doing.

What this has taught me is that strength is really a long-lasting adaptation. I've been adding 10 pounds per workout for both squat and deadlift for the last three months or so, with the last squat workout being at 370 and deadlift at 435. There were times when I missed a week and so repeated a weight or took 5-10 lbs off the next workout, so progress hasn't been perfectly linear . :-) Squat is starting to slow down, so I'll probably go to 5 pound jumps, deadlift still moving, though. Obviously, at some point this kind of progress will end and I'll have to modify things again (probably reducing deadlift frequency and/or going to alternating between haltings and rack pulls), but for now it's working in that weight is being added to the bar and my back is behaving itself within tolerable limits.

This has also taught me that I don't need to squat and deadlift a lot or do fives to see progress. But I think the strength I built up over the last nine years has an effect on that.

Anyway, that's my story, hope it might be of some help. Good luck with your progress.