Depends on the circumstances, really. There's about a $33k price difference between the 1LE tested by Motor Trend and a standard Z06. If you bought the parts yourself and had the know-how and skill to properly install them, I think $33k would be more than enough to bring a 1LE SS up to a Z06's level in all-around performance. But professional kits would probably end up doubling the price of the car(it's the labor costs that get you).
Personally, I'd probably go with a standard ZL1 and slap some R-Comps on it. That would probably bring it right up to a base Z06 on a track(though it wouldn't really help on the straights), and you'd still have some $20k left over for whatever else you wanted to do.
It's actually pretty surprising that GM would let the Camaro get so close to its halo car. But, then again, the C6 was already on its way out when the ZL1 and 1LE arrived, so maybe GM doesn't care that much about preserving the C6's image at this point.