Yea those sound great, until you factor in the extra wattage needed for those. Without overclocking he is already near 500w on a 600w PSU. The case only supports SFX and that 600w is the most powerful off the shelf SFX I know of (without designing one and ordering it custom) so I think both statements are kinda true. Yours is the most powerful theoretically, while his is probably the best someone has posted on the site power/square inch.
He could get a slightly bigger case that fits ATX PSUs, and the 5960X and R9 295X2 would still make it ever so slightly more powerful than this in bang per square centimeter.