We use to have a Standard products illustrated ignition book at work. It showed a picture of very type of points, coils and resistors. It gave your the resistance of the resistor. I went online to find that catalog. The online catalog shows you a picture abut when you click on description it tells you how popular it is and how much shelf space it takes up but not a thing bout the part. Everything is setup now to enter the year and make of car and a part number pops out. But when your modifying stuff you can't do that. You need the old catalogs which I kept. Every year we got new catalogs at work and every year I took the old ones home and updated my collection.
To give you an idea here is a page from the on-line coil resistors. In the 1980s catalog it would have told you if the coil had an internal or external resistor. It might have told you which of these resistors went with each coil. It would have told you the resistance value of each of these resistors. Half of these resistors could all be the same resistance and they just mount differently. Computers have not yet replaced books in the world I live in.
https://www.standardbrand.com/en/eca...ype=p&search=s