Hi! Long time no see,
Thanks for the piece of history! Maybe you already know this blog: recordandobicicletaszeus (I canīt post links either) It has a lot of info about Zeus.

Iīm having a terrible fight trying to rebuild this Torrot.

To my surprise, the Zeus fixed cup although it is french threaded 35 x 1 mm it is left-handed (it tights to the left) and I've learned it the hard way (after cuting it with a circular saw ) The bottom bracket is 118 x 55GS (Gran Sport)
Furthermore, I have already bought a new Zeus BB, same aspecs 118 x 55C (Criterium) but... A-HA! It doesn't fit, this one are both cups right-handed...