I don't think that the Giulietta switches will fit. Probably your best bet is to take your switch to a shop serving British classic cars and see if they have a Lucas switch that can be used as replacement. Lucas models PPG1 or PS7 could be possible candidates, see item #306 and #308 on this page. Other possibilities are models PS16, PS19 and SS9.
Can't help with part availability or interchangeability --- but I note your earlier post on a faulty switch. Yes, replacement is the best route but you may consider repairing your existing one.
On first appearance it doesn't seem as though you can disassemble but rmember they were put to-gether by someone or something. Normally - I'm not familiar with your particular switch - metal tabs are folded down to retain the two parts, carefully lever them back, taking great care not to break one off . Do it on a big bit of paper and slowly some small parts, springs may pop out and there are no manuals on this! But common sense and a little bit of luck you will find the problem. Usually dirt or broken contact. A second damaged switch may provide the parts you need.
As said not an ideal solution but my Super indicator switch was repaired as above - cleaning and some contact adhesive on broken plastic - and still works fine after 3 years.