Engine Vibration at highway rpm/speed

one thing I've learned over the years working on these old cars is if you are making changes to them and the car ran perfect before the changes, do one change at a time. That way if you notice the car is not running right after that new part was installed you know what caused it and how to fix it. I know that it's hard to do when you total restoration of a car and replace alot of old parts with new and you can not drive the car. I have had many friends over the years that replace many parts at once on a driveable car that have run into problems many people find after the new parts were installed and they have problems trying to figure out what has caused that new problem. Just my 2 cents worth!!!