[lolife99]

Do you know for sure what year spindles is on your 70 now?
63-70 conversion spindles?
70 trucks were drum brake.
Maybe someone has converted it with 71-72 parts already.

You have the truck.
Pull it apart and see.

The least you could do is swap 70 ball joints in the tubular a-arms.
I don’t know what parts are on your truck.
You are going to have to figure that out to get a real answer.
Everything from me is just a guess.