challenge accepted. I'll track down the relevant rule(s) and report back.
SO here's what I see, from an NCAA perspective (on the original scenario)
Original scenario:
4th and 5 on the B-30. A comes to the line and assumes an initial set in scrimmage kick (FG) formation. When the snapper touches the ball, Team A has 5 players numbered 50-79. A82 lined up as the right tackle. Team A then shifts, uncovering 82 and leaving him on the end of the line. Ball is snapped to A7 who is standing on the B-40. At the snap, A82 runs a route to the B25 and A7 fakes the punt and throws a pass A82 at the B25.
***
Rule 7-1-4 2 and 3:
2. All players must be either linemen or backs (Rule 2-27-4, A.R. 7-1-4-VIII).
3. At least five linemen must wear jerseys numbered 50 through 79
(Exception: When the snap is from a scrimmage kick formation, par. 5 below.) (Exception does not apply here, as it deals with less than 5 linemen numbered 50-79).
So when the snapper touches the ball, it is a legal formation.
When the shift occurs, uncovering 82, thus leaving him on the end of the line, 82 becomes an numbering exception, by 7-1-a:
7-1-5-a Any and all linemen not numbered 50-79 who are ineligible receiver(s) by position become exceptions to the numbering rule when the snapper is established.
However.
7-1-5 b and c:
(b) Any and all such numbering-exception players must be on the line and may not be on the end of the line. Otherwise, Team A commits a foul for an illegal formation.
(c) Any and all such players are exceptions to the numbering rule throughout the down and remain ineligible receivers unless they become eligible under Rule 7-3-5 (forward pass touched by an official or a Team B player).
Hopefully I got it right.