Here you're Taliking about something which is not real in the past, so you should use: Past perfect + (would + have + past participle)
The Past Unreal Conditional is used to talk about imaginary situations in the past. You can describe what you would have done differently or how something could have happened differently if circumstances had been different.
* If I had owned a car, I would have driven to work. But I didn't own one, so I took the bus.
* She would have traveled around the world if she had had more money. But she didn't have much money, so she never traveled.
I'm neither a teacher nor a native speaker.