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

Just throwing out some thoughts on this weird one. If you are getting spark but no fire, then that could be the firing order is out of wack. Also I know on early cars 64-66, if you are not in park all the way it wont start. Try putting in neutral and see if it does anything. Could be the neutral safety switch too ( if your came equipped). I also see you did not change the distributor, may be worth a try. Did you set the reflector gap to .08?. Also are the valves moving by chance? with 183,000 could be a timing chain too, assuming it was not changed.