Snell was great despite Lydiard's training methods, not because of them
Science has since revealed the importance of catering proportional development of different energy systems to your event, and strictly classic Lydiard systems comically miss the mark
If Snell had been trained by Peter Coe, we'd be talking about when, if ever, will someone break his 800 WR
First, does anyone know why Ventolin calls them wabbits?
Does he have a written lisp or could he be a relation of Elmer Fudd?
As for had Snell been coached by Peter Coe, the idea that he'd have run considerably faster is hypothetical. Yes, he probably would, but would it have made him 3 secs faster? I seriously doubt it.
I don't buy this 1 sec a lap conversion. If the track is in good condition it shouldn't be any more than half a second for guys at the top. Also, it was hand timed, which means electronically it was more likely 1:44.5. I'd say on a synthetic track it's worth somewhere in the region of 1:43.0 - 1:43.5. So, he's still got to improve by 2 secs to beat Kipketer's WR.
Snell was well over 1.5 secs slower than Coe over 400m and quite a bit slower over 1500m. He would have to have had to improve considerably at both ends. It's like saying Ovett would have been better training like Coe. He might have been worse. Just like Coe might not have been so good had he trained with Ovett's coach.
Of course Snell would be faster with more up to date training, but if you want to talk hypothetically, then Coe would probably still be the 800 record holder if he'd not been ill in 82 & 83, and if he were around today training the way El Guerrouj did, he would be considerably faster than his pbs over 1500, mile, just as would others from the past.