84 chevy pickup wont start

i have a 84 chevy 1/2 ton pickup and it wont start. i have replaced the battery and the starter. I have come to the conclusion that i am getting power to the starter but not from the the ignition to the starter. i have also replaced the ignition switch on top of the colmn under the dash and that did nothing. I dont know what to do so i was hoping maybe someone else has had this problem since i know chevy is horrible with wiring problems. If any one knows what could be going on i will accept any advice.

i had that problem and it was the last thing i checked, the ignition fuse

Neutral safety switch? Jiggle the shifter or put in neutral instead of park and see if it will go.