Oops, forgot the opamp exchange part.
The Mitsu 5219P is operated with rails at +/- 7.5 Volt, which means it is able to handle the full 50mA output current it is capable of. (at a reasonable temperature, 375mW matches the 75C limit of the thermal rating graph in the datasheet)
An NE5532/4 is not a terrific replacement i think, if only because it is not intended to put out more than 10mA, i have no idea why someone would pick an LM1458.
I'd say you'd have a better chance with a TL071, but to match the 10 times lower distortion number of the Mitsubishi you'd have to pick something more contemporary like an OPA134.
I'd buy an original, a dip8 M5219 is around $2/each.
(as only 1 of the channels is used, a SIP8 L-version would probably fit too, and the M5219L is cheaper than the dip8 version)