well as far as different bolts i have found some that are the correct size, but being as i am wanting to go axle over i was thinking it would be wise to beef up the hardware. using the current size would mean the thinner steel and i would want it as trong as possible. so i am trying to decide if its better to get thicketr steel but have to modify a bit or do not mods but settel for the smaller hardware.
as far as the bolt size, the plate pictured is for the larger bolts and they are 1/2" (original was 3/8"). would likely need to drill out the hole another 1/16-1/8 to get the bolt to go in flush and not be pinched/angled against the spring.