Downgrade the chrome version in WPT private instance

Our private instance is configured with several mobile devices which supports chrome 65 version and it is working fine.

However, I’ve another requirement to test the performance of application which runs on TC70 device in production and that supports Android 4 & 5 versions & still running on older version of chrome browser (30 & 34).

Can we add 2 extra devices in existing setup which can help to mimic current production scenario? else any other approach to test this kind of requirement?

Thanks in advance!!

Sure. You just need phones with those browsers and for auto-updates from the play store to be disabled. As far as I know, the agent should be able to control Chrome 30 just fine.