Good note on the Hub Centricity of the spacers. What brand are they and are they hub centric? Did the wheel alignment also put your toe into specs or was it just camber?
I'm sure it can't be your rims/wheel combo but just to make sure you could double check. A decent way to test out whether or not it's the rollers would be to put peter's rims on and try em out (Since we all know Peter has been hitting high speeds without any issues

). If you're still getting vibration then at least we know for sure it's a suspension component and not your rims.
You said that you only get the vibration when:
- Going Over 65 mph
- When turning steering wheel (Is it only when you turn left/right? Or does it vibrate either side?)
Sounds like some bad bushings to me. Probably inspect all your rubber parts (Including motor mounts) for any wear and tear.