mine are floating too....in my opinion thats the best way....
i made my cups....yours are not too short...you gotta dehump the arms(cut the humps off) and weld in plates flat where the humps used to be....
go to google and click on images and type in dehumped lower control arms...this shows plenty of arms that have been done...
dehumped arms is a must.... i did it to mine
this is one that hasnt been welded yet and you can see where he cut the humps off....this is done to stop the bag from rubbing on the humps....some people plate the bottom and dont even use a lower cup and bolt the beg straight to the plate