Ineligible players are permitted to go downfield as far as the expanded neutral zone on a play where a legal forward pass crosses the neutral zone, until the pass is in flight (ie, leaves the passers hand). The expanded neutral zone covers 2 yards beyond the defensive line of scrimmage. The rule does not technically depend on any type of blocking or non-blocking scenario in high school. There is some philosophy that comes into play with a lineman initiating a block at the LOS and continuing to block close to the 2 yard mark downfield. But just from a rules perspective, 2 yards is what is allowed.