Opening up the lash by 0.005 didn't change the peak power but it did add a little big of area under the curve. So I'm fairly well convinced that this particular cam wasn't what the engine needed. Maybe just a little too big.

It worked better advanced 4 degrees and with looser lash. To be fair, I did not do a lash test with teh 264/268 cam and I never tried anything other than 4 degrees advanced so I don't know if that cam is "perfect" or just closer to the target.