Beginner in Property Manager needs HELP! Canada

[Account Closed]

I got a chance to manage a 38 units building in exchange of free rent in Calgary, Canada (2 bd apartment that rents out at $1420) 

The building is currently making $48k gross rental income per month. When I took over it was making only 40k a month.

It has been 7 months since I started doing this and I really like and enjoy it. The owner has another building close by an I would like to manage that one too. He currently has 2 managers in 2 different units. One does the paperwork and the other does the the cleaning. Both are paying half of the rent but the owner does not like the idea of 2 people doing the work of 1.

I am having a meeting with him and I would like to talk about managing that building too. How much % or the rent should I charge for a 38 units building? What are the main points I should make to be assertive and get the position? how could I make this more convenient for him without giving up my interests($$) ? I believe this building is making 44k but I am not sure.

Thank you for your help!

Juan