Hi donwonnc,
I can't add much to this that others havn't already covered, do read the article that Paul has referred you to on his site re box dating, it's very informative.
One box did catch my eye, one of the red ones where a new number code has been placed below the original one. See snipped image.
Interesting to me anyway because that item 313/2H (4608) started production in 1956, but in 1957 they changed the entire numbering system from the former alpha-numeric coding, to a simple 4-digit numeric code. I guess they thought their production could never exceed 9,999 items !!
So that particular item was only called "313/2H" for just one year before becoming referred to as 4608. I'd be interested out of curiosity to know what the printing code on the box end-flap is if you could check and advise.
Nice items by the way, it's a pity you can't start building a layout, you have pretty much everything you need. On the other hand, as you say, most or all of the items are NOS, and we have to assume are in mint or near-mint condition (otherwise LN / Like New), original paper wrapping etc. The minute you start running them they are no longer in that state and you can certainly ask (and should get), a premium on your price.
I would suggest that if you find yourself starting to get tempted, you would be able to replace it all with identical items in tidy used condition suitable for running, for noticeably less than you will get for selling what you have. There may even be some enthusiasts who would be willing to give you a fair price for certain items, but also offering you the same thing to 'play' with as a trade-in, but that might only be of interest if you wanted to get into the hobby deeper. If you are simply wanting to make money from your very fortunate find (yep, we're all green with envy) then just take your time and they will sell, on Ebay, (or here)

There are no crooks here.
Finally, you can't delete topics, nor would we want to. One of the advantages of this forum is that it is also an archive. Who knows what some future member/s will find absolutely invaluable to them simply because it has been preserved here. From some of the recent topics, and new members coming on board I see this forum going through something of a resurgence and while there are other sites and forums which I also participate in, here is where I feel most 'at home' despite being a relative newcomer
The webmaster of course can delete topics or messages, should someone post something inappropriate or that they regret but in most cases a follow-up posting of explanation or clarification is preferred over outright deletion.
Good luck with your sorting and selling.
PS; I presume you have more than is shown in your pictures?, keep 'em coming, we LOVE pictures. You also mentioned a number of FALLER kits, some of us would love to see those also.
Cheers
Steve
cookee_nz attached the following image(s):