Linear Fusion rifles don't need to be their own weapon type in my opinion.
So why not make them Fusion rifles.
Make all currently existing precision Fusion rifles adaptive and move all Linear Fusion rifles into the precision Fusion Rifle archetype. Exotics like Sleeper, Queenbreaker and Arbalest can just be renamed to Fusion Rifles.
This would remove the underused Linear Fusion mods and possibly make Linear's more relevant in the game. You could for example use a special Fusion rifle combined with Sleeper and only use Fusion rifle mods, that would then benefit both weapons.