Problems with preload on 1 lifter, what to do?

[Killercanary]

OK, I have AFR pedestal mount heads, and an FTI custom cam. Last year I lived with a noisy lifters. I was using the stock pushrods but I had to cut down the pedestals on the exhaust rockers to get enough preload to quiet them up. Anyway, I replaced the lifters with new ones from FTI, and I got 6.300 pushrods for the exhaust. Well, with the stock intake pushrods, I was getting 1/8th turn preload, and with the 6.3 and a .015" shim on the exhaust I got 1/4 turn. Well, I started it and it was NOISY. So I got 6.300 pushrods for the intake now. Here's what I have now, on the intake I'm running 6.300 pushrods with the .015" shim, with this I'm gettimg 5/8th turn of preload. On the exhaust, I'm just running the 6.300 pushrods without a shim, and I'm getting just about the same preload as the intake. BUT, on the #5 cylinder, on the exhaust I only have a little over 1/4 with the 6.300 rod and no shim. I had this too when I ras running the 6.300's and shims on the exhaust, but at that time I didn't use the shim because of the fact that it was only at 1/4 turn without it. I noticed the helicoil was a little messed up on the bottom, so I cut the bolt down just a hair, but it didn't help, so the coil isn't the problem. I also put a washer under the head of the rocker bolt, and it didn't make a difference. Now, do I live with it since its within spec, or do I mill down this one pedestal to gain some preload? I don't know what to do... I'm at wits end. Thanks,
Paul