i have seen where in order to make some races people have mixed the better body mesh for humans with khajiit legs. and got it to work. i was wondering if i used an argonian upper body with khajiit legs by assigning them body parts while using the two body meshes. would it work?

Making a rat race huh? and uhm, yea, it should work.

It would work technically, in that the game engine will allow you to do it. However, it may not look quite right unless the body parts match up correctly. In particular, the stock bodies definitely don't match at the waist, which is why a lot of stock pants cause issues on the better bodies models.