Interesting that you say you are at the end of the age spectrum so you won't be diving deep or doubles. I tend to be on the older side on dive boats I frequent these days (OK, I am usually the oldest guy on the boat - 67), but I don't have any problems within recreational limits of either depth or time. Moreover, others who dive with me (who have more serious external indicia of aging - e.g. heart problems of one sort or another) don't seem to have any problems within recreational limits either. Since you seem to have been diving for some time, did something happen that made you decide that 60 feet is as far as you think you should go?
FWIW, my pony bottle is 30 cuft and I wouldn't have it any smaller <g>!
(I ask this for my edification. If you don't want to say anything in a public forum, I would understand.)
Regards,
<TED>