should we learn from Salnikov? or Kieren Perkings even?

I think late beginners should. or you should be prepared to learn to kick.

What about 1500m technique? Has it changed much? Would your technique still work today?
It is almost the same, but not really. I took 40 to 50 [strokes] for 50 meters. Now top distance swimmers like Sun Yang and the Italian Gregorio Paltrinieri do 30 or 32 which requires more strength and more power applied to each stroke because the distance per stroke is much greater. And now, because the tempo is slower, they kick more frequently. I was dropping my legs because my arm stokes were very fast and I didn’t have time.  Now, you see some people swimming 1500 free with a six-kick beat per cycle (a cycle is two arms: one arm and the other) – which is normally a sprinting technique.  Now the world record is 14:31:02, or about 27 seconds faster than I swam, but in some competitions – some international or European competition – I could still be in first three with my best time. With my best time, I could even be a winner.

http://www.fina.org/news/swimming-then-now-conversation-vladimir-salnikov-rus

400m Salnikov
https://www.youtube.com/watch?v=Q236baSnKSM

perkings 1500m
https://www.youtube.com/watch?v=_26oohYp96c

Males are not swimming like that anymore, but woman do
Pellegrini
https://www.youtube.com/watch?v=O5Tg8d2TmoU