There are several major qualifiers there, and the linked article discusses it appropriately and in context. That linked article is about moving the saddle forward on a frame with a very very slack seat tube angle and an unusually long top tube. That first generation 52cm Sam Hillborne has a 71.5 degree seat tube angle and a 57.5cm top tube on a "small". The author has already put a short stem on to partially correct the reach. A typical 1980s road bike like a Centurion may have a 73 or maybe even a 74 degree seat tube angle. That means that the saddle setback on a Hillborne would start out more than an inch further back. A zero-offset seatpost on a Hillborne and a mega laid back seatpost on a Centurion would likely achieve a similar amount of saddle setback. On my own Sam Hillborne, with a small setback post (Nitto 65), my saddle is near mid-rail, biased maybe a couple mm forward. On my vintage 1980s bikes, I slam the saddle back as far back as it will go. Many of us oldtimers remember the standard saddle setup of hammering one's saddle back with a rubber mallet.
If your Centurion has a 71.5 degree seat tube angle, and you've already shortened the stem as much as is appropriate, adding a zero offset seatpost is a worthwhile next step, just like the article. A zero-offset seatpost on a typical 1980s road bike would result in more of a triathlon/time trial/aero bars kind of fit, which may be OK.
For context, my experience has been as a 'decent' bike fitter in 15 years of working at bike shops in my youth. Maybe 1000 customers asked me over the years to slide their saddle forward because they were too leaned over. Maybe 800 of those 1000 agreed to try sliding it back instead. Maybe 500 of those 800 were surprised to see that it helped a lot.
I hope it all works out for you and you get the fit you are after.
Bill Lindsay
El Cerrito, CA