/6 electronic distributors
You will need the 4 or 5 wire sub harness that attaches to top of spark controller (orange box) if using one, or a very reliable GM HEI conversion can be used in place of orange box which does not require special harness. Where you are installing in a truck, the advance curve may need to be changed from what a car would use. Trucks are heaver, push more air when up to speed, placing bigger load on engine so curve needs to be slower to come on, and full advance should be held back several degrees from where a light car’s engine would like it to prevent detonation.
There is a lot of info on timing curves for /6 powered cars & trucks over on slantsix dot org for one’s reading pleasure, and probably on this site as well.
Also one of the members, Duster Idiot, at /6 can build you a custom curved electronic distributor if you don’t want to mess with finding correct mechanical advance governor, replacement springs, and dealing with all the trial & error recurving your own part takes.
http://slantsix.org/forum/viewtopic.php?p=367329&highlight=recurve+price#367329
http://slantsix.org/forum/viewtopic.php?p=363069&highlight=recurve+price#363069