My 1996 Toyota corolla 1.6 sat for a year not being started . I now have it running new suspension system and rack and pinion with less that 500 miles on it all cv joints etc all new . no vibration at 55 mph except when going up a small hill . 60 and above noticeable vibration . steering and handling unaffected with no loss of power .
Aside from having your wheels balanced there is not much advise I can give without further inspection. But that would be a good place to start. Try to take note if the feeling is in the steering wheel or more in the seat. If you notice one more than the other you can swap the front wheels to the back and test to see if the vibration follows. If it does, you know for certain the issue is in the wheels/tires.