Have you had the tires/wheels rebalanced?, Does the shudder go away above 55mph? What kind of condition are the shocks in? How bad are the tires worn?

Vibrations through the steering wheel is normally caused by out of balance tires/rims, bad shocks, tread seperations, or severely cupped All of the other stuff you had replaced tends to cause wandering, and uneven tire wear.

I would have the tires rebalanced, also have the rims balanced to make sure that one(or all) aren't bent. Also have the tire shop balance the tires for a higher speed(depends on the machine they have).