Both the mowers you seek come up now and again. Ebay often have the rovers, but it depends on which year model or title your after.
A few members here may know more about the Vortex availability.
Since its a crossover serial, Id say its still 58.
Snorkels come up occasionally in NOS and SH, so keep your eye out.
Yes Avocado hammered finish by Galmet is still available, but its expensive and depending on who you go through will depend on shade. Rarely are 2 mixes the same, even though they use the same Two codes. Mitre 10 Will still mix by order only. Spray cans have still not been reinstated in this colour either for shelf stock or special order.
Most restorers have now pretty much made Wattle Deep Brunswick Green the Uniform colour for handle bars and Bracket, and Delicious Red for the Victa Logo.
That cowl and tank assy with decal and cap would be desired by some collectors due to its original condition and patina and the fact it was likely off an Auto. Check your cap and see if the inner is green or white.(just for my own interest)
Perhaps you could sell or trade this for a std setup with money going your way...Just a thought for preservation:)
Overall you dont need much except a snorkel and recoil starter if you wanted to go this way.
Even though your wheels aren't shot, keep in mind that they stopped making them again, and are getting up over 150-200 for a set.
Enjoy your hunting and restoring...If you need any info on history or parts and accuracy please don't hesitate ask:)