I have Langdon's mini HEI. Everything worked well on my truck before, it started fast then, it starts fast now. The most noticable improvement is the smooth very low rpm idle and low speed driveability. It is also more forgiving during warm-up.

1962 Fleetside 4spd 235 w/O.D. posi 3:90
In the Stovebolt Gallery
1990 Subaru Legacy Wagon AWD 2.2 5sp
2013 Ram Tradesman C/V
My Webshot Photos]