Don't worry about blowing up the engine by revving it up to drive 55 MPH. If it blows up, it needed to be replaced anyway.
These engines are noisy. That does not mean it is suffering.
30 inch tall, narrow rims and tires will help you reach 55 MPH at a lower RPM. I suggest you try that first before you go to the trouble and expense changing to 3.55 gears.
That Ute is beautiful and needs to be on the road and often!
