I'm taking my first journey into electric flight and I need some help.

I have gotten a small rocket powered glider that I want to make some modifications to.
For reference you can see the model here: [link=http://randrmodelaircraft.com/Gamma%20Star.htm]Gamma Star[/link]

The directions show how to be able to have this as a boost glider or an electric pusher. I want the best of both worlds so I have decided to put an electric motor up front while keeping the rocket motor in the back. This is going to require me to make some modifications to the design but I want to keep it as close to the original as possible.

Due to size limitations I am forced to use a brushless inline motor.
I will also need to run a folding prop.

Where I need the help is in motor / battery selections.

I would like the plane to go around 60-70mph and last 5-8 minutes (time is less important) under electric power.

Here is what I know:
Plane: ~383 grams (includes electronics and rocket motor less battery)
Brushless inrunner: ~ 100 grams
1350mAh 3S battery: ~126 grams
ESC : ~18 grams

Total weight should be around 627 grams or 22 oz.

Due to space constraints I would like to keep the diameter of the motor 24mm or less.
Length is less important.

I'm looking for motor / battery / prop recommendations.
Any help will be greatly appreciated.

I will provide any information I can but my knowledge on electric is next to nothing at this point.

Thanks,
Norm