I agree that the Speedway bushings are relatively hard. An additional source for softer urethane bushings is from the parts section of Pete and Jakes (peteandjakes.com). They also carry 3/4" - 16 rod ends that accept either 1/2" or 5/8" bolts, and a weld-on sleeve that fits the urethane bushings. These bushings are 1.75" OAL and 1.25" diameter at the sleeve.The availablility of the weld-on sleeve is a nice convenience, because as Murphy's law predicts, the size and wall thickness of DOM tubing that was needed to fit the bushings was hard for me to find locally.
Hope this might help someone.