You need a end goal and a build plan and a budget. Do not buy parts that do not match your end goal.
The value of swapping in a bigger or more modern engine that makes a lot more power to start with, cannot be discounted. A Big block fits that car very well. So does a LS series engine.
Local and Federal EPA smog laws must be considered before you dig in. Keeping the car smog legal should be part of your plan.