What is the range on those magnum torches exactly? is it a radius of 64, making the diameter of the no-spawn zone 128 ish, or is it a 64x64 area around the torch?I use square grid (every 64 blocks) of magnum torches at level 45 around my main areas, which allows me not to worry too much about lighting up to level 90 and make really efficient mob farms. It could be cheaper in a triangle grid, but I would probably mess it up.
Also, what about the shape? is it square? There are so little information about this thing...