I think you are going to be disappointed if you are looking for
wrought product in this alloy. Miralloy trade mark for a plating
process that puts a coating of copper tin and zinc on parts as an
under plate before gold plating. There is also a casting alloy of
copper tin zinc that is not used much anymore but you may be able to
find someone who still makes it but with that much tin and zinc in
it it is going to be too brittle to work as wrought material.
James Binnion Metal Arts