Suggestions 71 340 duster daily driver - alternator? distributor?

You can buy a $45 HEI distributor from Skip White on ebay. Put another in the trunk for extreme reliability. A normal square-back Mopar alternator should keep your battery charged fine, which is all an alternator need do. Easy to get (thru 1980's), cheap, and reliable. A Denso is smaller, neater looking, and affordable once you pay for the custom brackets.