I notice that the distortion is fairly high when the output voltage swing is only half of the power supply voltage.
14V p-p is 4.95V RMS which is only 3.1W into 8 ohms.

I do not see any frequency compensation to prevent oscillation.

 

I set the same output voltage as in the original circuit (almost). The original circuit with normal (not idealized transistors) has a distortion of more than 1%. Moreover, I do not think that distortion should be considered at maximum power. In simple circuits (with one cascade of voltage amplification) it is possible to do without correction. In this case, sufficient stability of the amplifier is obtained without correction.But correction can be entered.

 

The distortion will be reduced, especially the even harmonics, if RC1 is boostrapped.
If we keep adding parts then its performance will equal a cheap IC but cost much more. Isn't that called "schoolwork"?