very good friends to all. I bought this primus kitchen no 535 and I noticed that it has a large part of the Radius components. its previous owner adulterates the kitchen or is there a manufacturing history???
I guess your stove was made in 1963 or 1964 as Optimus had aquired Radius then and used up the stock of Radius parts on Primus and Optimus stoves.
I think the tank looks like steel sheet welded in an automatic sheet welder and then nickel plated - this indicates a relatively modern serial production - could be 1960's or maybe later but I still think 1963 may be the year. Can you find a year stamp on the tank? Possibly a circle with "A""letter""number" inside but more probable a row of 6 digits were the last two "6*" would be the year?
I still think the tank looks homemade, never seen anything like it from Primus nor Optimus. But for a homemade tank it looks good.