Hi Tjames,
Welcome to the ODK Forums, and congrats on picking up a 'classic workhorse' Victa.

Our Pic & Vid how-to is at;
https://www.outdoorking-forum.com.au/forum/u...images-or-docs-to-my-post.html#Post87412Keeping the 'patina' can be done, but it depends on how deep the top surface rust has eaten in, and how extensive it is. .
Start off with spray degreaser and nylon scrubbing brush, then water wash and air hose dry. That will show how much of the original paint has remained bonded to the metal.
For the deck underside, a 'twist knot cup brush' on a 100mm angle grinder gets the crud off really fast; but be careful about PPE.
I wear a leather apron, full face shield, and long welders gloves for that job; after having been impaled [through clothing] by shed bristles a few times...
We can go into suitable rust preventives/paints for underneath, in due course.