On my VFDs you can use an external switch for forward/reverse but you have to attach to the VFD's terminals that are for that option and then change...
I have a RPC supplying power to a 7.5 hp 3 phase motor, so I only have L1, L2, the generated Leg and Ground through the extension cord to the motor....
OK, assuming the head works properly and can generate 9 cfm at 300-350 psi, but I only need 125psi to blast, wouldn't the 100 gallon or so tank allow...