The conversion of the project was successful.

The new directory structure is as follows:

F:/Workarea/cascode/1
    cascode01.opj
    cascode01.dsn
    cascode01.dbk
F:/Workarea/cascode/1/cascode01-PSpiceFiles
F:/Workarea/cascode/1/cascode01-PSpiceFiles/SCHEMATIC1
    essai.sim
    SCHEMATIC1-default.mrk
    SCHEMATIC1.als
    SCHEMATIC1.net
F:/Workarea/cascode/1/cascode01-PSpiceFiles/SCHEMATIC1/essai
    essai.cir
    essai.dat
    essai.mrk
    essai.out
    essai.out.1
    essai.prb