Front disc 6 lug conversion LCA question

[FoMoCoGuy]

So I'm doing a 6 lug disc/power steering conversion for one of my parent's neighbors with a 64 c10. I have all the parts needed, but I noticed that the shaft on the lower control arms is a lot larger than the ones for the stock 64 arms.

Do I need to go back to the junk yard and figure some way to get the rivited on "perches" off the vehicle I pulled the LCA from, or is there some other way to do this? IIRC the vehicle was a late 80's under 7200# gvw 3/4 ton van.