If you are fast say around 4.6 speed play full back. If your a lot slower than that then you should play line. But if you lose the right amount of weight and work hard to get stronger and quicker the options are endless.
If you are still 5'10 260 and quick for size you will be needed for O line but if you like the attention then D-line is for you. If you don't like the line then possibly Fullback or Linebacker but get ready for physical punishment for those are tough guy positions where you hit and get hit constantly
Cheerleader.
Defensive tackle
RunningBack
fullback?
If your fast: cornerback or wide receiver
Punter or placekicker. No speed required.
Anyone you choose! - Most coaches would have you on the line
In 7th grade you would probably be an offensive or defensive lineman.
cornerback or safety
at that height, probably better to play safety, too short for cornerback.
wide receiver if ur fast...goodhands. safety if not maybe cornerback
corner back