Technical when fitting a 36 ford crossmember into a 40, with a 8''

using stock 36 radius rods
...
i have the radius rods - 36
i have a flatter 36 rear crossmember - going to switch it in
are the springs the same?
2.5'' wide
how do you do the rear tube shocks
when I make the weld in tab
do i make it so i lower the axle in a bit?
do i reverse the spring now?
do i fit the radius rods wider than stock
use a wider bush at the front?

anyone got anypics of a similar installation.
thanks