[Mr70]

I don't think that's right.
Embossed ignition coil numbers were not calling out the bracket offset for the vehicle they were going into,but rather an abbreviation for the last 3 digits of the actual Delco full seven digit part #.
In general,what set coils apart was the difference in the resistance wire they were wrapped with internally.
#202 coils measured 1.8 OHMs,#238 coils measured 1.3 OHMs,etc.

Chevrolet did use different coil mounting brackets w/varying angles,so using the examples above:
A 1969 Nova SS used a #1970344 coil mounting bracket.
A 1969 Camaro Z/28 w/flat hood used a #1971011 bracket.
A 1969 Camaro Z/28 w/Cowl Ind. hood used a #1966876 bracket.
I've yet to see a coil body reflecting anything close to the above bracket numbers,but would like to hear from anyone who has.

Why the application difference between a #270 vs. #293 vs. #298 on essentially the same engine may have had something to do with static interference,(mast antenna vs. one imbedded in the windshield which began in 1970),or even an overheat issue in a specific vehicles engine bay,or something as miniscule as using up old inventory for a newly designed coil.
I'm trying to learn too..