1973 318 - daily driver for years - now won’t start

I agree with ^^^^. Check for spark first if your getting spark check for fuel in the chambers if that checks out it has to be a timing problem either timing chain skipped or broke it the distributor is loose and turned. If no spark at all I'd start with a multi meter and check coil its possible you blew a fuseable link in the wiring and not getting power to the coil. If you are check and see what the voltage is at the plug wire.