I don't have much to say really, I think your points regarding are strengths are spot on, but I think the question in the whole Messi vs Lizarazu and Eusebio vs Makalele is who will have the better supporting cast. Yes Eusebio & Seeler are great combination I won't deny it, but you have to take into account the fact that their facing off a trio of Makalele - probably the best water carrier in the world, Schwarzenbeck - who was a stopper designed to stop especially the type of Eusebio's and make sure the ball won't even reach them, and Hansen who is probably Liverpool's best CB of all time and was good in passing his way out of trouble. Add that to Schnellinger who pushing that much forward you've got a very very solid backline against the threat of counter attacks from 2 men basically, maybe 3 if Masopust or Czibor are quick enough to join. These long balls that will be sent to them are exactly what Makalele and Schwarzenbeck excelled defending against and it plays directly to our strengths. We'll have more men behind to effectively fight that front two.
On the other hand, the minute Messi gets a foot over Lizarazu with his quick breaks to the middle, there's so many options! He can find a pass to Sivori in his classic to Neymar/Alba style of pass, he can pass it between the Costacurta(who needs to come out to him) and Scirea(who has Charlton roaming as well) for the relentless movement of Elkjaer, he can pass it back for one of those deadly long shots from Charlton who is bound to find space, or he can even take his shot or try to beat Costacurta as well!
And the biggest difference between our teams is not just how much more Messi is built to cause more damage here than Eusebio against the defenders their facing and setups they have, it's that we have more goal threat than "Messi" where they are very reliant on Eusebio magic on the counter. When Messi is being doubled with Masopust or Edwards or Costacurta, it's Charlton who will find these spaces and Sir Bobby is one of the best United players in history, and these deadly shots he had are bound to find the net at some point with so many players going Messi's way and our forward's movement.