You continue to speak about Lydiard, without understanding athletics totally changed.
The big change is the speed of long run, and of long tests on track, that many years ago nobody used to do.
For example, Michel Jazy, european record holder of 5000m with 13'24" and 1500m with 3'36", every year started again his preparation running till 3 hours at a pace of 5' per km : something completely useless, and according to what we currently know, almost reaseable.
In 1979 the WR of 800m was already 1'42"33, so at the current level, when the WR of 10,000m was 27'22" of Henry Rono (and improved of more than one minute) and the Marathon record was 2:08:34 (Derek Clayton) in a marathon arguably a little bit shorter, so we can consider at the end of 1980 the real WR the 2:09:01 of Gerard Nijboer.
On 28 September 2003 Paul Tergat was the first athlete able running the Marathon under 2:05 in 2:04:55.
Currently, his time makes him the 47th performer all-time, and there were already 75 performances under 2:05:00.
To think that nothing changed in training is absolutely ridiculous, and only somebody nostalgic of the past, but without any knowledge about the present, can suppose everything is like many years ago in training.
About all your equivalences between 800 and 1500m, these are speculations (and not analysis) that consider only what can confirm your hypothesis, and not all the real situations.
For example, what do you think of Sydney Maree, 3'29"77 with only 1'48"8 in 800m (but also 13'01" in 5000m) ?
What about Caleb Ndiku, whom I know very well because is a my athlete, able to run 3'29"50 with a value of 50" in 400m, but also 7'30" alone in 3000m ?
And when you look at the OFFICIAL personal bests of the athletes, do you really think that Ronald Kwemoi can run only 1'49"7 in 800m, or El Guerrouj 1'47"18, when was able to finish the last 800m in WCh in 1'46"8 ?
If you want to discuss about training and level of performances, you need to better know the athletics of today, possibly cleaning your mind from the idea that everybody is doped.
Athletes with good talent (but not top champions) can run full marathon under 2:06 without many problems, when there is the right mentality and not the fright to run too fast. And this doesn't depend on the fact you are African of white, and doesn't depend on any doping. It depends on the mentality of big groups, because in Kenya and Ethiopia every athletes joining a group of marathon runners, including one of the top in the world, knows that athletics only : when they speak about their race, it's normal to look at splits under 62' in the first half for every kind of race, and also the beginners know that need to stay in those groups during the race, if want to finish inside the official prizes.
Maybe you forgot that, in 1985, the best European were able to run 2:07:12 (Carlos Lopes, 37 years old) and 2:07:13 (Steve Jones, completely alone, without any pacer, with a crazy 61:43 in the first half). And arguably they could run around 2:05 (maybe under) in a marathon of today, with rabbits and big groups of athletes running together very fast without thinking too much about tactics and saving energies.
Very simply, European and American were no more able to combine VOLUME and INTENSITY, something they were able to mix before 1990, while the African did this in natural way, and when they find an expert coach able to use in the best way their mentality, they can run very much faster than many years ago.
ENDURANCE is not something general, but SPECIFIC. This means that the Aerobic Power for a specialist of 1500m is the ability to run fast a competituon of 5000m, and in training running already very fast distances till 15-18 km ; for a specialist of 5000m, running fast till 18-22 km ; for a specialist of 10000m, running fast till 30 km and in competition to be able running fast HM ; and for a specialist of Marathon, running fast HM (because the full event can be run at a percentage of the Aerobic Power), with specific long run (not always, but sometimes) at a percentage of 95-98% of the Marathon Pace, also reaching distances near the distance of the race.
For whom is able to understand this process, doping is totally useless. For whom doesn't want to run too fast in training, EPO can give some advantage, but not at the level to produce better results compared with clean athletes, using right training without fearing volume and intensity.