Um... I know Mikami is listed as 61 years old or something in his readme (which is still kinda young for elderly imo), and he has more of a deep/strong voice instead of just elderly sounding... (Which also might not be exactly what you're looking for if you wanted like, a really elderly voice or something...)
I'm not too sure of many others though, I'm sorry.. orz
Oh yeah, also forgot C. Hamanekku as well.