One of the problems you have there is that all your weapons and knives are on the pack ... the first thing that get's ditched in a fire fight is the pack ... at least that is how it works in the military ... because you cannot be effective with it i.e. move/ go prone and still shoot ...
It would be better to work in "stages" ... develop a "belt kit" using military webbing which has the "core basics" ... water, water filter,gas mask, food, ammo, metal cup for cooking, fire-lighting gear, washing gear, navigation kit, medical kit, binos and "ONE" knife ... a Basic 9 is my choice but anything like a SAR 8 or a lightweight similar knife is all you will have room for but carrying a multi tool works too in addition to the main knife. I put in a down jacket that can fold away to a coke can size for emergency night time warmth in a pouch and have a gore-tex bivi bag on the belt webbing. All this I can "live" with and then look to weapons ... because "running away" is still an option with what is then carried. I like a silenced .22 pistol for "food" ... plenty of ammo can easily be carried ... and it works for "overt" weapon use rather than "defensive" use ... I usually have that in a shoulder holster beneath my smock.
Then you want a primary defensive weapon ... take your pick ... shotgun or a rifle ... lightness counts and one is all you would need ... if it gets "bad" and your still living ... plenty of others will be lying around.
Your main pack has supplimental stuff ... food, ammo, sleeping bag, kip mat or hammock and more advanced first aid supplies and spare boots/clothing but only one set of each.Stuff you can ditch if you need to and come back to if you survive a contact.
In many years of being in the military "gas masks" were often seen as a PITA ... but in natural disasters where smoke and dust and even ash if it is a volcanic disaster or air bourne radiation in small doses as per Japan ... the gas mask is a key bit of kit ... one extra filter is best off on you and others in the pack. Do the same with a water filter.
NBC suits are a bit of a waste IMO ... a water proof layer which can be washed down and dust removed is about as good as you can expect if radiation is an issue.
However, you don't really want to be carrying as much as you are .... way too many bits and pieces there .... 60 lbs is what works best and that includes water. If you are "moving on foot" you have to trust in your skills to re-supply food and water ... not try and carry everything. The same with ammo and/or weapons. Catering for "long term" survival is all about knowing what to carry for a few days survival ... and keep "re-supplying" as you go ...