starting up 340 that's been sitting for a few years

try sanding the points too (at least). The 289 in my '66 Mustang had points, and I had to sand them a bit fairly regularly to keep it running tip-top.

btw, sitting for a few years shouldn't be a problem- my Scamp sat for over 4 years after I bought my Stealth- when I decided to get it going again I added some gas to the quarter tank or so that was in it, put a battery in it, and it fired right up. Ran fine, too- people will give horror stories about what happens if a vehicle sits for a while without running, but they're mostly bunk.