Noticed today with about 80 more miles on the cams that the idle does drop pretty low and the car goes lean (18:1 or so) when you brake hard with the clutch in (vacuum drops to about 15"). Then the car gradually recovers to 14.7:1 and the idle smooths out and the vacuum come back. It's not a big issue and I was able to alleviate most of it by adding fuel at 800-1000 rpm with SAFC in the low throttle setting, but it was noticeable and something that I'd guess you wouldn't see with 264/264.