Instead of distributor timing, how about valve timing?? You’ve advised that your mechanic found the crank pulley bolt loose, and tightened it to 70 ft/lbs. Factory spec is 94 ft/lbs, and who knows what damage was done prior (or since) that tightening? Sadly, a good portion of the mechanical issues that you are describing in your various threads, can be explained by a sheared keyway. Hopefully this is not the case, but perhaps it is now time to actually look at the crank and see???