Nick
Two sizes:– No.1 with 2-inch rotor, and No.2 with 2½-inch rotor. They were designed for direct coupling.
Running speeds were 3600 to 4200 rpm for the no 1 and 3200 to 4200rpm for the no 2.
Sirius produces 1/3 bhp when running at 2800 rpm at 50psi so should work nicely,I hope.
Stuart