Starter/solenoid/ignition/battery problem

[MikeMcCl]

I have a 1972 C10 long bed with a 350 small block and a 4-speed manual. About a week ago it was running really good it ran the wrong and healthy. But as of Friday I tried to crank it over and it made a weird clicking noise I asked my Auto Tech Teacher about it and he told me it was the solenoid and I replaced it. I replaced it today started it up it ran really good. I turned it off five minutes later then tried to turn it back on it and they gave me the same weird clicking noise. I was on the phone with my Auto Tech Teacher for about an hour-and-a-half today going through every little thing trying to figure it out and we both came to the conclusion that it's probably going to be the starter. I talked to my dad about it and he predicts for some reason it's the alternator which I don't understand how it would have anything to do with it. The battery is less than 6 months old . But after digging through wiring and burning my hands constantly on the Block and the headers we're predicting it's one of two things either the starter or the ignition switch. I would like some sort of input on this from you guys. I am slowly figuring this out as I go. I'm not much for electrical I am more of mechanically minded. But this is my senior year Cruiser and I would like it to have it done because this is my last week of school. Help would be much appreciated thank you very much.