Try locking it out and set the timing around 34 or 35. Maybe more with decent gas.
I know, it won't work. But try it.  A 340 w/ that much cam is gonna need a loose converter and want some rpm. If you don't lock it out, at least run somewhere around 25 degrees initial and the light springs.
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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