Regarding PEDs. Definitely cocaine is a PED especially where fatigue and pain relief are useful, and in fact opiods are known to have been used as PEDs since ancient Greek times. In fact that is why we call it "doping" in the first place. In the late 1880s most competitive cyclists specifically took cocaine which was acknowledged particularly among French cyclists. Also recorded cases of lacrosse teams using it.
In the 1904 Olympics apparently "Mixtures of strychnine, heroin, cocaine, and caffeine were used widely by athletes and each coach or team developed its own unique secret formulae."
I can go on about that, but regarding steroids they knew about that since the 1940s. Russian weightlifters were publicly using testosterone by 1954. American Olympic athletes were known to be doing them by early 1960s. With professional boxing getting fed from Olympic boxing it is not a stretch that there would be significant steroid use starting in the mid 1960s.
Note too of course that it wasn't even illegal. Steroids were readily available since they had legitimate uses. Boxers already had doctors giving them special attention and all they would have needed for a testosterone prescription would have been to say they were getting too sore or tired.
I know by personal experience that by the mid 1970s every highschool boy had access to steroids, so I'm pretty darn sure that every pro boxer did as well. Whether they chose to use them, who knows, but I feel every one of them considered it since it was a tool for sports performance that was gaining prominence in all strength and endurance sports.
