First you should take a look at this e-book

EVERYTHING YOU WANTED TO KNOW ABOUT ELECTRIC FLIGHT
http://www.rcuniverse.com/forum/m_7100376/tm.htm

Then I suggest you post some links so we can see the specs for each part of the system.

Airplane
motor and gerbox, if any.
ESC
Battery
Prop specs

Then we will know what you are planning to use and how things will match up.

The Motor, Prop, ESC and battery have to be well matched, as you realize, so we need to know the specs of each component to help you match them.

What level of performance are you shooting for? Scale? Sport aerobatics? 3D? All our pattern flying?

Once you look over the e-book, the reason for the links and the questions will become clear. Right now we are trying to help you match things based on little information. And since this will be an expensive conversion we need as much information as possible to help you get it right.

How did you decide on that Hacker motor?
What that ESC
Why a 5000 mah pack?

Ihave no ideas how you came up with these.