They will work fine as replacement transistors. If the circuit is that finicky, then something is wrong with it.
Note that the circuit does not include base-emitter shunt resistors across TR1, TR2, TR5, or TR6 which limits performance and is generally not a good idea. This indicates that the designer was either being cheap or did not know any better.
The 330K resistor across TR1 makes sure that the circuit starts up.