Scrimmage Kick Play - Penalty Enforcement

[NVFOA_Ump]

4th & 8 at the A-2.  A is in scrimmage kick formation and punts from their own end zone.  B-22 positioned at the 50 yard line runs up and fields the ball on the fly at the A-39 yard line and returns to the A-35 yard line where he is forced out of bounds.

During the kick there is a flag down for an illegal block in the back against B-25 at the A-49 yard line.  What do we have for penalty enforcement?

[Kalle]

IBB is a basic spot foul. Basic spot is the PSK spot at A-39. The foul is by the team in possession and behind the basic spot, so enforce from the spot of the foul. 1/10 for team B at B-41.

Rules 2-33, 9-3-6-PENALTY, 10-2-2-c, 10-2-3

[NCAA-SJ]

Line to gain is A10?  Did we start on the goal line?
 

[NVFOA_Ump]

It was a strange series.  Started after a stop at the goal line with the ball just 1 foot outside the goal line.  We actually got this enforcement right but had 3 different opinions on how to enforce before actually deciding what to do.  Looks odd to end up 20 yards behind the PSK spot but that's what the rules clearly (well maybe not so clearly    ) say.