Okay. I think I got it: you mean the clone being made immediately an 8 year old (as opposed to what I thought a baby), and it remained 8 year old without change for ten years. However, to my mind, it's still wrong to say the body's 40 year old. Although it actually breathed for 10 years more than it existed, one shouldn't forget the eight years it immediately had by default. That's me and picking on technicalities.
I never imagined memory Snape as a horcrux - as you've said, there's no indication to that in the text, - rather to the contrary. But my mind goes all screwd up from phrases like 'his soul is still intact (albeit missing a piece)' or 'Snape's soul is still wholly residing inside Snape, just inside different vehicles (physical body, stored memories)'. So is it inside *Snape* or the 'different vehicles'? And how can a thing be intact while missing pieces? Just trying to find sense here. In fact, the real question is the possibility of storing a soul inside a pensieve. Not that I doubt Snape's academic innovations.
*feeling vaguely ridiculous for picking a good read apart onto details that have little to do with the said work's literary merits*