Engine Vibration at highway rpm/speed

i'm sorry guys...my brain is fried from this day and i'm trying to remember things from 2014 when I found out I had a cast crank in a 70 block and thought for sure at the time that changing to the correct flexplate and balancer would have fixed it. after all I've done now...i'm just throwing my hands up and about to give up. pinion angle sounds like a good place to start as was suggested. I appreciate that suggestion. I guess I will find out about the rims/tires tomorrow after I get the new ones mounted and take it for a spin. this car is just a driver and we have owned it since 1989...I was 8. i'm just trying to make it as good as I can get it so I can enjoy it...but the vibration is enough to drive me bonkers.