'70 1 ton disk brakes

[chopttop]

I have a '70 C30 cab/chassis w/a Franklin motorhome on the frame, don't use it as much as I like cause of the drums. Decided that I am going to put disks on the front this winter. Been doing a quite a bit of reading and sounds like purchasing a complete cross member from a '73 - 87 C30/C20 and rebuilding it as necessary, would be the way to go. Read somewhere that the dually fronts were a little wider to match the rears, would getting a front off a C20 matter that much ? Would like to lower it a bit but doesnt seem that their is much out their and don't think I want to go the cost to bag it. So swapping out crossmembers sounds like the way to go. Any input on lowering or anything concerning this project would be appreciated.