What i would do is to remove the new HEI and bring up the 406
to TDC (Air coming out of #1) re-install and go from there,you
did not say what kind of car you have so just be sure that the
HEI is getting a full 12v power supply.Your basic timing with
vac advance dissconnected should be around 8-10 before TDC
if your not running vac advance it should be the same.

You should be ok from there..not all engines are the same,so
you have to play around with what works best,i think after you
replace the HEI it will make a huge difference on how its running,



Good Luck..And i hope this helps some...