Rafael, It is possible to use a 25 fps workflow for film out. In the end it is a frame for frame process. You work with PAL all the time so there is no learning curve, sound post is uncomplicated and all that needs to be done is the final sound track needs a pitch alteration to compensate for 24 frame projection. Avoiding 24 versus 23.976 is advisable.
Unfortunately sound on 16mm is awful. Mono optical and really poor quality. Finding a facility to scan to film is important though to find out the file formats they want. You might want to consider sending the job to Australia. I have contacts in Sydney who do this sort of work and understand a 25 fps workflow. Let me know if you want contact details and also if you want the audio pitch corrected which I can do.