I did mean 46rh, but if I don't have to mod the floor with the 42rh then hell I'll do that :) remove the upper hoop? Like, the upper hoop in its entirety?
The 42rh will need to built up for your HP, but yea the upper hoop needs to be removed. Here is a thread detailing it: 42RH / A-500 in a Duster with pictures.
You can also buy the crossmember already built from US Cartool.