Ok, .so you turn the key to start position and nothing [ no starter crabk]

Couple of simple test
Jumper wire from terminal #30 [ red] to term. # 50 [violet ] on ign sw . Starter should crank [ make sure shifter is in N or P ]
If yes, replace ign sw . If no . see is starter will work in 'N". If yes , replace neutral saftey sw.
If niether , pull 3 prong connector on firewall between engine and brake booster, to the left of booster , and jump power from bat + to the center terminal. If yes, starter circuit between ign sw and connector is at fault.
Let me know what is found.