Much easier to remove the oil filter to access the bolt on the bottom of the distributor. I set my 67 at 5 degrees Before TDC as prescribed and it runs great. No pinging at all, plenty of power. Of course it's completely stock.
It's a San Francisco car. There is some body panel rust and small holes in the front floor boards and trunk floor but the underside is super clean. Runs good, drove it home 140 miles.
It was later than 1970/71. I think it was 1975 when catalytic converters were first widely used on automobiles. Those demanded the use of unleaded fuel.