A Quick Phoneme Question!

Hello all!!!

I need to use phonemes to explain the weak pronunciation of "have" in the sentence:

He shouldn't have insulted the policeman.

When speaking it sounds more like:

He shoudn't've....

So would the "have" here be written like:

əv

or maybe:

ʌv

Or maybe something completely different????

This is all rather new to me, so I would really appreciate it if someone could help me out here. And I will also apologize in advance if I pop up here with similar questions in the near future; but I think this is the best place to check and see if I am understanding this stuff properly. :)

Thanks a bunch!!
"Lilith"