i have jun 272s. i just went thru the 1st phase of my motor's break-in period. the idle was rough at the beginning at 15.8:1 AFRs. i since dumped some fuel in there and got it down to 15.0:1. i also increased my idle to 950 RPMs. which i feel isn't too bad.
before that, the car would frequently stall when i hit the brakes and the RPMs drop below 600. now, any stalling is very rare, and i can still live with the car being a daily driver. i might raise the idle to 1K RPMs once i get a reflash.