Chemistry was listed by an India outfit that probably would want you to buy a boat load (ingots for remelt, not bar stock).
Any non ferrous foundry could make it if they were interested enough.
That's SAE's job - writing down what things are made of so they can be duplicated. They call that STANDARDS.
But having an SAE number does not mean it is laying around for sale in the form you would like, especially for stuff with such narrow application.
I do know it is totally missing from the UNS book (Unified Numbering System, put out by SAE and ASTM), which lists just about every metal and says what it is related to and what its chemistry is and who standardized it.
850.1 / ASTM B179 is similar, and is listed in UNS.
5.5-7.0 Sn
0.7 - 1.30 Cu
0.7-1.30 Ni
0.70 max SI
0.10 max Mg
0.10 max Mn
0.20 max Ti
0.50 max Fe
remainder Al
850.1 is just a more "speced" version of 850 which has the same amounts of Cu, Ni and Sn.
John Oder