After doing a little research I found McMaster Carr carries the perfect shoulder bolts. In case this is of use to others in the future here is a link to them below (part #94496a420). 1/2" diameter shoulder to go through the bushings and the right length (2 1/4") to go through the end plates and bushings.
Ordering 4 this morning and will fab up a set of end plates.
https://www.mcmaster.com/#94496a420/Measured my old bushing studs and they had worn to just over 0.25 inches from an original 0.5 inches. That is really some wear!
