Maybe you can find an old 'valve' (vacuum tubes for yanks) color TV to scronge one from.
Been there done that, in 300-500 watt range usually about 1.5 turns per voltage, maybe a little less for 50 Hz as the core has to be larger then 60 Hz.
You will lose effective permeability on the core because it is unlikely you will get the laminates back together again as tightly as original new core.
Thought you would get a kick from the attached homemade 'Caribbean' arc welder transformer.