That's a decent enough circuit, but it's designed for headphones. It won't deliver 3W into a 4 Ohm load. R7L and R8L will drop too much voltage for a start.
It will need to be beefed up considerably, to drive a 4 Ohm load with a decent power level.
You're right, I forgot to mention that I lowered the emitter resistors R7/R8 to 2R2.
Also, I lowered the feedback resistor R4 to 20K and base resistors R5/R6 to 5K6. But this is inconsequential.
See attached schematic of my version. The power supply is a 24V center-tapped transformer into a full bridge and a pair of 4700uF bulk caps.
Since I've built it a year and a half ago, it has been serving as my main desktop computer amp driving a pair of 2-way bookshelf speakers measuring 3.8ohms. It can be quite loud a 2ft. As per the waveforms screenshot attached, it can produce 4.24Vrms into 3.8ohms at just below clipping. That puts the power output at 4.7W (V^2/R). Also attached is a frequency response analysis.