No, there are no other indications of power.
Comparing modern compressors, 5 cfm would seem to require 1.0 hp approx to 120psi. What's throwing me is the size of the induction ('asynchrone') motor frame, it's 7" diameter and over 10" long, about the size of a modern 3hp unit, although I know motors tended to be larger then.
Alan
