I dont know, its a big laser and in homeworld it was the mainstay of the battlecruiser class, though my memories from that game were from the complex mod which added a lot of lore friendly ships.
I believe that the laser needs to do good damage (not enough to destroy anything one shot unless they are frigates) but there needs to be a hueg drawback after using it , either forced to vent after using it as it basically uses all the flux and there is a hefty cooldown so the next shoot is far apart. I am not too kin on limited ammo for weapons as I like extended engagements. But having to wait long times between shot, or shooting it forces you to vent your flux or disables all other weapons for a short period would do the trick .
The upside of scarce ammo would be that it can still be
very powerful, like a torpedo weapon, with a decent fire rate(for a finisher type weapon). Compare that with some of the large missile weapons, they never really seem to run out during battle.
In addition, you can increase the ammunition with expanded magazines.
Although an upscaled tachyon lance with longer cooldown could also work.
There is also the problem of it being fun to use.
A drawback like driving up the flux of the ship up and forcing it to vent or disabling the weapons sounds more annoying than anything else.
So ammo or long cooldown sound like the best options.
I would recommend taking the SWP Yamato out for a test run to find out how the wave motion cannon feels like and then decide on it.