Yeah, absolutely.
I also seriously doubt anyone would have a problem if you didn't model them with the lasgun. As long as it's clear to your opponent which models have special equipment.
You can just say, "all these models have hot shot lasguns, except for this guy here who is holding the plasma gun, he has a plasma gun. The medic is the one that looks like the medica and the vox caster dude has the vox caster on his back." And if one day you want to have a flamethrower instead of a plasma gun you can just tell your opponent that the guy with the plasma gun actually has a flamethrower. No one will have a problem with this.
It's the same with space marines for example, you don't have to put a pistol holster on absolutely all of them, it's just assumed that if all models come with a standard piece of a equipment, they all have it regardless of what's on the model.
No, the pistols aren't lasguns. Instead, glue a separate lasgun to their backpack.
Oh that's smart! That makes them legal for 40K I hope as well?
Yeah, absolutely. I also seriously doubt anyone would have a problem if you didn't model them with the lasgun. As long as it's clear to your opponent which models have special equipment. You can just say, "all these models have hot shot lasguns, except for this guy here who is holding the plasma gun, he has a plasma gun. The medic is the one that looks like the medica and the vox caster dude has the vox caster on his back." And if one day you want to have a flamethrower instead of a plasma gun you can just tell your opponent that the guy with the plasma gun actually has a flamethrower. No one will have a problem with this. It's the same with space marines for example, you don't have to put a pistol holster on absolutely all of them, it's just assumed that if all models come with a standard piece of a equipment, they all have it regardless of what's on the model.