Causes of slow spark?

I remember when i had my 68 coronet parked on a sidestreet in dowtown winnipeg, no plug in for a block heater. If it would turn over,it would start. Choke setting was bang on though.

That being said, slow cranking is related to battery,cables and starter. Direct drive starter or gear reduction?
I preferred the bigger starter on my 318’s.
Alternator belt has always had a way of telling me i have a kinda weak battery (lol), but it does the same jumped to another car and cranking fast