Statements like "2.0 running 6.2 peak" mean that the manufacturer is being honest with you about the true output from the motor. Less honest manufacturers would simply call it a "6.2 HP" compressor. That's the max horsepower, as I'm sure you know, which can't be generated unless there is a whole lot of torque being developed, which probably can't happen when used for a compressor.

You're right, the SCFM figures at 40 and 90 are comparable, and since that's what tells you if you can use it for a particular application, these figures are all that matter. 90 for air tools, 40 for a spray gun.

Congrats on your find. Sounds like it should be a decent setup.