Lipseals in the given dimensions and fitted with a stainless steel spring are standard industrial stuff which should be available more or less everywhere.
Important is to grease them properly.
We changed the lipseals on our 54 in 2016. They were available in an industrial suppliers store "round the corner". Because there was some wear in the sleeve we smoothened it. There was no need for a replacement. The shaft sealing is properly working since then.
Mago del Sur 54#40