Look closely at the two axles. The original is a torque tube drive axle is mounted on pivoting spring perches where the open drive 1955 1st series spring perches are different and won't allow for direct swap of the entire axle assembly. Unless of course you decide to change to an open drive and get rid of the torque tube which causes multiple other changes to make it work. You had said before you weren't interested in doing that.
As mentioned by Fibonachu, drilling out the rivets and reinstalling with bolts may be your easiest solution? Others that have tackled this will chime in to share their experiences I think.
