Set it at idle. Bring the RPM up to verify if you like, Should stay the same if there aren't a bunch of worn out parts in it. It will still move around some with a stock type set up. Lots of parts involved between the crank shaft and the distributor cap. Put a crank trigger on it and it will be rock steady. 
CHIP
'70 hemicuda, 575" Hemi, 727, Dana 60
'69 road runner, 440-6, 18 spline 4 speed, Dana 60
'71 Demon, 340, low gear 904, 8.75
'73 Chrysler New Yorker, 440, 727, 8.75
'90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt
'06 GMC 2500HD LBZ Duramax
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