There is one partial total conversion mod for TSL by Gsccc (he released it but it wasn't fully completed, a couple of planets to play through I think); I haven't myself played it, but I have heard it is quite good.
Post of interest;
http://www.lucasforums.com/showpost.php?p=2452048&postcount=64)
Partial Total Conversion? Is partial total an oxymoron? Sorry I just thought that was funny :D. Anyways, that was just a Demo of a mod I was making a while back... which I am currently making now, but am revising quite a bit... if that makes any sense at all. I would be amazed if it did because even as I am typing this I have no idea what I am saying :/.
Anyways, most of the Total Conversions are in production at the moment, I believe Revenge of Revan is a story addon, that does quite a bit of... converting, new weapons/planets/characters and all that stuff. DarthJebus mentioned already that he has one coming out soon as well.
It is going to be a very good modding year I think :).
-Gsccc