vibration prob, please help

[tandk22]

hi i have a 69 camaro and i have vibration issue. my car is not a frame off resto, just adding parts when i can. motor is a 454. it is at high rpm vibration comes on most notable around a hundred in 5 and 6th gear, gets bad. vibration is in the seat and shifter. i have a new richmond 6 speed tranny, only 600 hundred miles. heres what we done trying to find it:
went through the tranny, many issues but did not solve the vibration. new high speed rated tires and rims( had them rebalanced), wilwood brakes all the way around, new strange drive line, checked and double checked, new richmond gears ( rechecked lashing), new moser axles ( they came with run out had to machine them). please help, what would be some options to trace it down. i want to do track days but i cant til i solve this. would a chassi dino help maybe. thanks