What would be the best position to play in tackle football for 12 and 13 year old boys?

These are boys with many years of experience playing tackle - they have all played different positions from defensive line, tight end, wide receiver, and running back. These boys are fast runners, quick and agile, but all weigh 105-108 lbs and about 5' 0 - 5' 1. They have to move up in divisions this year thus being teamed up with and against older boys who are taller and heavier but not necessarily with more experience. The bigger ones run slower so they generally are going to be d-liners and tackle. What positions would utilize these boys speed, agility, and experience to the best degree. No offense, but if you don't know anything about youth football, please don't answer with a wild guess.