First time 3X R2 Mag build. Questions about driver etc...

I am planning on using a Mag 2d to mod into a triple r2 light(on a tight budget also, due to being in college). My first question is whether 3 p60(26.5mm) modules will fit into the Maglite head?

I want to use these leds.
http://www.dealextreme.com/details.dx/sku.15943
These reflectors for maximum throw.
http://www.dealextreme.com/details.dx/sku.5937
And this driver.
http://www.dealextreme.com/details.dx/sku.26106

I plan on using two quality 2500mah 18650 batteries in series, and was wondering if this would work. Also, since the driver says it is for 5 leds, will running 3 leds in series overdrive the leds and burn them out? And if it does not the specs say it runs each led at 800 mah, will this achieve near maximum output without jeopardizing the leds, or should I look for a 1000mah or 1.2 amp driver( I have little knowledge in this area)?
Thank You

The driver will work off 2x18650 and it will be fine with just 3 LEDs
You'll get about 700ma to each LED see Eprom's testing thread
You can raise the current to 1A by changing the SMD resistors.

However you won't fit 2 of those reflectors in a D head, 3 reflectors is right out.
Its only 50mm across inside the head.
Aim to keep the diameter of the reflectors under 22mm.
Or use a triple reflector (needs the threads on the edge sanded off)

Or an optic like this that will fit

Get the glass lens 5-pack too they are so much better than stock plastic

You'll need a heatsink to mount the LEDs onto, like Download's multisink

For a triple, I would use some of KDs 20mm reflectors

You could build a quad emitter and using DX's 18mm reflectors

Thanks for the responses guys. Any idea as to what output I should expect t 7-800mah?

Well about 600lm you can see some lumen testing data collected by jtr1962 in this post
https://www.candlepowerforums.com/posts/2990597&postcount=303