wrt "swiss threaded parts" - the fixed cup of the bottom bracket is the only "swiss" dimension fitting on the machine so it is not much of an issue. nothing to be a-feared of.

the bicycle's tyres appear they may be original, hutchinson? this tells us it has not been ridden very much in relation to its age; appears in very fine shape for the annuation.

about all one need do is disassemble, clean and lubricate. then reassemble. lo' and behold "robert will be thine uncle."

if she is a good size for you then by all means do just as devinfan suggests: "keep & ride."

if i wanted to do a couple minor improvements i would add toeclips and straps, change the delrin shift levers to metal ones and do as devinfan suggests fitting a quality saddle. its your bum so no one here can tell you what model will be most comfortable.