I've tried two different setups on my salvager since 4.85 released, both had their pluses and minuses.
Setup 1:
6x Zoner Gunboat Turrets
With that setup, I was easily able to take out most fighters and bombers that decided to attack me. During one scenario I was fighting four xenos at once - three in crow HF's and one in a civ bomber, and I took out three before going down. In another, I was attacked alone in orkney by a Gallic Brigands Bomber and a Gallic Brigands Light Fighter - killed both of them without more than a few scratches to my paint.
This setup is good for defensive combat, when the odd fighter or bomber comes after you, especially if you can overcome the salvager's size and lack of manuverability with good flying skills. Problem is, it cant do jack to gunboats, and isnt really effective against other transports (You can still beat just about any transport out there, but you'd do better against them with razors/pulses).
Setup 2:
2x Gunboat Razors
2x Gunboat Pulse
2x Gunboat Missiles (one on the forward-only hardpoint, one on the rear-only hardpoint)
This setup I've only used in two real combat scenarios so far, when people were trying to pirate me or just attacked for no reason. The first was against a corsair praetorian bomber that was trying to pirate - I tried to RP my way out of it like I usually do, but he would have none of it, so I unleashed with a pulse -> Razor -> missile salvo. In that one instant I took his shields down and left him with about 10-20% hull as I took off at thruster speed into an asteroid field where I could get to cruise.
The second fight was against an outcast gunboat that attacked me, and a fighter joined in against me late into the battle. Needless to say, even with heavy weapons like razors and pulse, the salvager doesnt stand a chance against enemy gunboats on it's own. Gunboat shield regen and their ability to fire more heavy weapons gives them a huge upper hand.
Against transports, this setup would work rather well, since you have heavier weapons to take down shields/hull - but remember, if you ever try to pirate in the salvager, you need someone else with you that has a disruptor.
I'm currently using setup 2, but I'm going back to setup 1 as soon as I can get to a base that sells the guns again. I just prefer the faster weapons for hitting fighters/bombers, and no setup will let you take gunboats effectively. I'd like to use IMG turrets or something similar instead of Zoner turrets, but unfortunately I'm not able to without posted reasons, and there's really no reason I can think of other than "on the black market, lol?"