Don't make her parents a factor, if she likes you and you like her think of it this way, now your in different grades and its kind of weird, but if a 45 year old man marries a 43 year old woman nobody says anything. Make a decision on your own but don't regret it later. If she likes you her parents will have to deal with it.
If they really love her they will have to respect her decision.
Questions like these are completely based on your morals. It is best to set them and stick with them. Set limits.
Personally, no. I wouldn't have a problem with a 10 year old being with an 80 year old if it weren't for laws. I wouldn't but just sayin.