From what I have seen don't run an inline at 3000 RPM constant, the problem is harmonics, when I drove my car on the street you could not see out the rear view mirror at 3000, it would vibrate so bad, above and below was fine.
Hmm. My Firebird currently runs down the highway between 2,700-3,000 rpm, and when I pulled the engine for the last overhaul I had three of the six flexplate bolts be essentially hand tight. I wrote it off as me possibly be inattentive, but now I wonder. They all got Loctite on them and definitely torqued to spec this time.
I'm re-gearing the car soon with 3.42's because it's what I have with an actual limited slip carrier. That'll make cruise around 2,100 rpm.
I hadn't given much thought about the torque converter (unlocked) possibly acting as a fluid dampener. Hmm.
