Cannot find SPICE models of audio transistors for LTSpice?
To be sure, I'd have to see the schematic of the circuit you're using these transistors in but I am 99% sure that you can replace any of these transistors with any other general purpose NPN or PNP transistor for which there are models available.

These transistors are Bipolar Junction Transistors or BJTs and these have the nice property that their properties are mainly determined by physics instead of how they're made. They would all operate at Vbe = 0.6 to 0.7 V for example. Other important parameters are the current gain beta (Hfe) and the maximum collector current Ic.

So for the MPS8050, beta = 300 and Ic,max = 1A
No have a look at the transistors for which there are LTSpice models and check what their beta and Ic,max are. These don't have to match exactly, a beta between 200 - 500 and Ic,max of more than 0.5A would be OK.

Since you're just using them in a simulator you cannot blow up the transistor when Ic becomes too large, the transistor breaking down is not modeled !

Also, a proper design does not rely very much on transistor properties as Vbe and beta as these can vary a lot and not only when the temperature changes. To reverse this, if the circuit you simulate would only work properly with the transistors you mention, I think it is a very bad design.

Since you're using this for audio, this is very low frequency so almost any transistor is fast enough.