My 2 cents (in no particular order):
Gunzerking = must hipfire = you want weapons that have good hipfire characteristics. He’s actually a great user of hyperion weapons, though they unfortunately have anti-synergy with Steady As She Goes (whereas other guns benefit from it, it makes Hyperion guns worse). Salvador has some of the best fire rate buffs in the game, and so is naturally suited to using weapons with large magazines (long time to empty mag versus reload to be more precise).
If you run 5 Shots of 6, then ammo cost is an important variable to think about, as the way that skill works is that it lowers shot cost by 2, which means that a weapon with a shot cost of 1 ends up costs -1 ammo, or otherwords, it gains +1 ammo, which will go in the magazine if there’s room. If the weapon has shot cost of 2, then it becomes 0 instead (note that you aren’t getting ammo back now), if the shot cost was 4, then it’s reduced to 2. The end result is that the effect is much better for weapons with lower shot costs, prime example being Vladof RLs (yes it works on launchers, though it only affects main hand weapon).
I’ve noticed that if you activate Gunzerk when you are below health gate, you will rapidly regenerate 50% of your max health at the start in addition to the usual slower regeneration (2% of max/sec iirc), so a nice strat to maximize your tanking ability is to hold gunzerk until you are healthgates and then pop it. This does however increase risk of going down during Gunzerk, which can be bad if you don’t have Down Not Out yet (I haven’t had many issues though, so it’s plenty manageable).
The off-hand weapon’s crosshairs don’t expand due to sprinting like the main hand do, which means you can fire with full hip-fire accuracy as soon as you exit a sprint with the off-hand.
Because of Gunzerk regenerating a % of max health, health boosting shields can be very effective on him for NVHM play. The Flame of the Firehawk that you will get from the relevant sidequest is a good shield on him, since he prefers fighting up and close and hence under usually near constant fire (Nova spam ftw).