Question about supanova reflector

I am new here so first of all, hello.I would like to ask about light distribution.

I have 600w supanova shade. It is dimpled with closed ends, which are painted gloss white. Know the one I mean? The original supanova I think? Also it has got a double curve to the inside dimpled reflector bit.
What I would like to know is what is the maximum area I can cover with this shade effectively? It seems to spew light out almost horizontally out of the sides.
Is the area square or does it cover more area width ways (parallel to the bulb) or what? I remember reading that the supanovas have an excellent "spread" and I want to make full use of it.
I will probably be hanging it about 20 inches above the tops. Do you think it would effectively cover an area of 1.5 * 1.5 metres instead of just 1 square metre?
The plants will be short to medium in height done NFT.
Is there anywhere that I can find the specifications for this particular reflector?
Thanks.
Oh while I'm at it.... which particular make of 600W HPS bulb is the best at the moment in your opinion? Am currently using Son T plus.
With these two things I want to try to get maximum light from my reflector, without using a light balancer.