A diagram would help here. Key points are:

1) How much gauge (distance between the widest point of each boat) was there at each stage of your diagram? This helps address the question of Rule 15 compliance. 15

2) Where were the boats at the starting signal? (A boat has no proper course before her starting signal.)

Here are a couple of tools that you can use for that diagram:

Mac:
https://sailreplay.com/

Windows:
https://boats.sourceforge.net/

Also, is this a fleet race, team race, or match race? I ask since Rule 17 (same tack, proper course) is deleted for match racing. 17

How was the initial overlap established? Specifically, was it established in such a way that B was limited by rule 17? As Al says boats have no proper course before the starting signal so leeward may luff but if 17 is on leeward must fall off to no higher than her proper course (usually close-hauled) at the gun. 

Also recognize that if boats luff "beyond head to wind" they've changed tacks and windward & leeward have switched. If the boats change tacks & change back that turns 17 off. 

A  couple of things
1. There is no proper course before the start so 17 does not apply
2 . After the start if the overlap was established from astern  (back door) 17 does apply and L cannot sail above proper course.
3. If L was luffing to clear the pin end of the line that is their proper course, but once clearing the pin they need to come to a close hauled course 
4. If 17 does not apply then L can luff head to wind. If they go past head to wind they have tacked and broken the rule. 
5.  When L subsequently bears off if they overrotate to do so and there is contact it is all on L.  If they bear away and do not overrotate then W was not keeping clear. If there was no contact in that situation no foul

Facts:
1)starboard tack A is windward,   starboard tack B is leeward
2)coming  to the start line,  boats are slightly overlapped  and approaching start line
3)B luffs at A, A responds by heading up 
4)After cross start line B continues to luff A after clearing the start and is well beyond head to wind
5)A responds by coming up and hails B sail your proper course B continues to luff A,  then B comments:  if we have contact I will protest you 
6)A tells  B again to sail a proper course B abruptly goes bow down 
7)A goes bow down almost same time trying to avoid contact with B,  
8)B stern just misses hitting A amidships by inches but no contact occurred.

On 1) it has to be clarified wether RRS 17 is on, or RRS 11 only
2) no rules broken either way, as long as B respects RRS 16
3) if full after start, and if RRS 17 is there, B breaks RRS 17;  if no RRS 17 is on, no rule broken, as long as B respects RRS 16
4) B looses his rights on RRS 11,  as passing head to wind, she's "tacking", so subject to RRS 13:  she must keep clear from A. No need of a contact to determine wether a boat has been keepng clear or not. Apparently, A did not. So B breaks RRS 13
5)  B intimitades A for a Right of Way she do not have (she's under 13), B breaks RRS 2 and possibly RRS 69. 
6) 8) B tacks again of starboard, and by missing A for few inches, she do not keep clear, so B breaks, for the secon time, RRS 13
7) while B tack abrutly, A was ROW, and she make all  that was possible to avoid contact. Chapeau.

conclusion:
B DSQ for breaking RRS 13 twice (maybe also breaking RRS 17, but who knows), a DNE for breaking RRS 2 and, possibly, PC  starts an investigation about what exacly happened  (wordings, tone, manner etc etc) on 5) to acertain wether B should undergo an hearing under RRS 69. 
Well, i would.

All… Jim hasn’t provided any updates, but I might guess that when he wrote “luffs well beyond head to wind”, that maybe he meant to write “luffs well beyond close-hauled”, given the other descriptions surrounding that statement. 

well, if 17 was off, and no 13,  no rules broken, beside, possibly, a 16, at position 6), maybe...

if 17 was on,  B DSQ for definively breaking  RRS 17, (position 4), maybe 16 (at position 6), and the possibility of  a DNE for breaking RRS 2 (position 5) and a 69,  depending on wordings, tone, manner etc etc, (a gentle reminder out of kindness, or an intentional intimidation, knowing they are not ROW?): difficult to tell, in this discussion. But the risk for B is there, and myself I would check that in the hearing.

If boats were on starboard at pin end it is likely port would be the lifted tack. If windward boat was not there, is it not likely that leeward would tack to port and cross all the starboard tack boats. Surely her PC in the absence of windward, would be to luff to HTW and tack onto port. So why would R17 prevent that.