Welcome to the forums!
I really like the idea of largos having two forms and having a chance to get the one or the other form and producing unique plorts, or rather have the two plorts they would normally poop out be combined into one!
But I'm afraid if you try to turn them into another form from there on you will end up with Tarr because largos eating plorts different from theirs will be turned into Tarr
Also keep an eye on the Development Roadmap
here so you can check what updates are already planned and you know what will be coming in the future :)