Do the cheap and simple checks first.
1974 car so age related deterioration might be a cause.
Are you getting fuel through ok?
How old are the plugs and leads?
Any air getting sucked into the fuel lines/carb?
The short run after cooling down then recurring problem might be heat related. As a component warms up it can expand causing air to leak in, failing electrical components change when warmer etc. Check the vacuum system that feeds to the distributor. Warming the pipes can cause leaks in weak/ deteriorating pipes.
I’ve had misfiring due to failing plug leads years ago. New leads sorted it. A 17 year old car with what looked like original leads. Carb, coil, distributor/ condenser all checked ok.