I don't think any operating characteristics are going to be critical to that circuit, so you just need to meet or exceed the voltage and current ratings. https://www.digikey.com/en/products/filter/transistors-bipolar-bjt-single/276?s=N4IgjCBcoGwJxVAYygMwIYBsDOBTANCAPZQDaIALAAxwDMdIh1cFtVIAuoQA4AuUIAMq8ATgEsAdgHMQAX0IB2CohApIGHAWJkQtABxUArPE49%2BkIaMkz5IAExgqEaCD4CAqhLG8A8qgCyuOjYAK4iuIwgIQIAtgCCkTGSAjBU7LYOVLQqbhae3n6BwWERhNEWAGqJyRbUcoSZCC65IPm%2BAUGh4ZHlIDEA6tUSKXaG9SAAtHYqaqIhWiSQ5GMcsmtAA