Help wiring ignition wire on 5.3 swap

[josueh95]

hey guys im almost about ready to fire up my 5.3 in my 76 c10 swb. The last part im having some trouble with is finding where i should connect the 12v switched cable that was provided in my harness. Now i hooked up the 12+ battery cable to my started and a positive cable from my battery to the starter also, i took out the entire wiring system from the engine bay when i did the swap so i dont have a cable runing from my starter to the ignition

there is a ign source labeled on the fuse box, do i just tap into that wire with the 12v switched cable?
also from where do i get the cable that runs to the starter? thanks for any help guys