I'm the owner of 'this blog' mentioned in an earlier post. The needles I use in my Singer 12 are a Groz-Beckert size 80/12 DBx1 - note they do not fit all Singer 12 as they have a larger shank than the original 12 needle made by Singer. The Groz-Beckert I believe have a smaller shank than some other DBx1 needles.
Your machine looks lovely and very like the German Vesta TS machines I have. My German TS machines take the normal modern needle 15x1 so it would be worth a try - does your machine have a needle stop at all? If not you will need to adjust the height of the eye to just the right place to get a perfect stitch.
Also you need to remember with any round shank needle you need to orient the eye in the correct direction - for a TS machine it needs to face the front.