I think we should follow the guidelines we more or lesh stablished in Di Stefano's thread: rating players from what we really see in the videos. We know football was different back then, pace and style of play were slower, defending was much less 'aggresive' than today and based mostly on zonal defending (if I'm not mistaken man-marking was in fact an innovation of the 60s). The fitness of the average player of the 50s was also laughable if compared with the average player of today, that's why true athletes like Gento, Di Stéfano or Eusebio were able to shine so much over the guys around them. Passing speed was usually pretty low and 'soft', with almost unexistant through passes. Etc, etc.
So it's clear that we need to revamp pretty much all sets from that era. I've already done Hidegkuti, and while it's possible he may need further tweaks, I can tell he feels real ingame, and can still be very effective and dangerous even playing against players in modern-day standards. What we cannot have is sets like Kubala's, which makes him pretty much an all-round unstoppable player. Or people like Eusébio or Puskas with SP 97... it's ridiculous. If you see videos of them you can tell they could kick the ball pretty hard, but it just can't be put in the same league of Adriano Leite, Roberto Carlos or CR7. Balls were different, pitches were different, boots were different, players were different. To be honest, I see Eusébio in a similar level to someone like Forlán, with mid-orange SP, while Puskás can live perfectly with a low orange.