Hi and Hello, is it Brat?
Sunbeam Specialties has a lot of the parts for Alpines, and I found most are interchangeable on my Sunbeam Venezia. The Venezia is mechanically a Hillman Minx. Also a strang bird and little known in the Rootes community.
For some Lockheed brake parts I had good luck at JEM Vintage&Classics in Hinckley in the UK. Also Rootes Spares in Holland has a lot of parts and was quick to ship me some parts.
As the Singer Vogue is so unusual, certainly here in the US, and especially an estate! KEEP her ORIGINAL is my opinion. (I might even be interested if you decide to sell). Robert