Lets take this by
the rules:
R74: Pass, parts are legal
R75: Pass, tanks are rated for 125+PSI
R76: Pass, parts are unaltered
R77: Pass, parts are legal
R78: Pass, this rule lists the parts of a pneumatic circuit, but not in any specific order
R79: N/A not a compressor
R80: N/A not a compressor
R81: Pass, not operating above 120PSI
R82: Pass, beyond the primary regulator, and working at or below 60PSI
R83: Pass, though white-listed to be useable in 120PSI, not specifically required to be there
R84: N/A not a pressure gauge
R85: N/A always on-board
R86: Pass operating at 60PSI or less
R87: N/A not a relief valve
R88: N/A not a pressure switch
R89: N/A not a vent plug
R90: Pass, operating on a single solenoid
No blue boxes are applicable either.
So, since this passes all applicable rules related to pneumatic, I say it IS legal