Stuff was legal at the time so it would have been a lot more potent...not only that, he was a genetic freak
My man, you know that people get legit Test from the pharmacy all the time, these days. There are TRT clinics that'll hook you up with 200mg/week of pharm-grade test, easy. And some people, who have found unusually permissive doctors, can get far more.
Also, in some parts of Europe, e.g. Bulgaria, testosterone is available OTC at pharmacies, no questions asked. My Euro bros head down there all the time.
The pharm-grade stuff today isn't inferior to the pharm-grade stuff from the 1970s...
And I can tell you right now that 100mg/week is a low TRT dose, even if the testosterone comes from Schering or Bayer. It won't do anything for your physique unless you're laughably low-test to begin with. Even back in the late 90s, when people tended to recommend lower doses, 500mg/week of testosterone was considered a beginner's cycle.