Consider this, please:
Person A: My brother was supposed to appear for an interview at 8am, and now it's 10. I don't know if he got the job or not. But one thing is for sure,
If he got the job, he would be very happy now.
If he got the job, I would assume he is very happy now.
If he had got(ten) the job, he would be very happy now.
If he had got(ten) the job, I would assume he is very happy now.
Are these sentences all correct?