What is wrong with my car?
Ok if everything is original i can almost guarantee it a timing gear, this is not an easy fix. In 1974 they used a nylon polymer toothed timing GEAR instead of a timing chain, so what happens when it goes is it breaks into pieces and falls into the oil pan (pain in the ***) so in order to fix it you need to pull the entire engine, because you cant drop the oil pan if you don't. clean the oil pan of the debris from the broken gear, then you need to take the front of the crank case off witch will expose the timing gear, replace it, along with the gaskets, then put it all back together.
i would spend some money to have a pro do it if you are not to experienced because there are a TON of things that could go wrong doing this job.