Any ideas on the age of this Mark II FSS

Hi all,
I live in Stockholm, Sweden, and 2011 I did buy a used Mark II FSS.
I think it is still in pretty good shape although I do have some questions to the forum.

Firstly, how old do you think it is? The serial number is 373838.

The stock is synthetic (black) and there is only one screw holding the barrel to the stock, strange isn't it.

The accuracy is good enough for me, but unfortunately the threads in the "nut" of the action (The one and only for the barrel screw) is a bit broken, It still works, but I have to be very carefull when detaching and attaching the stock, any ideas how to fix this?

Lastly, I think I have done a misstake ordering a new laminate stock, http://www.gunpartscorp.com/ad/1433130.htm, this was probably not the smartest thing to do since it is supposed to fit an Mark 2 LV. Now, having found this forum I have learned a lot of the different types of Mark Ii, and I have understood that this will not fit sporter barrels. My first problem will probably be that the barrel channel is much larger than the barrel... Any hints on how to "fill the gaps" that most likely will appear? I have not yet got the new stock, but I think it will reach Sweden within a week.

I would really appreciate answers to any of my questions. (Sorry for my bad english)