If period correctness is not an issue, a modern cassette hub is the better choice. The problem with old freewheel design is that it puts the drive side bearings in the center of the axle where the weight of the rider can bend or break the axle. Modern hubs either put the bearings to the end of the axle or use an oversize axle that can take the load. Other ...
Rico was a bicycle manufacturer from Switzerland (Wallisellen, a town near Zurich). Rico PF means "Rico - Paul Fries".
You can check some badges on the swiss auction sites, to try to pinpoint the production year. For example:
https://www.ricardo.ch/de/a/rico-velo-rad-marken-schild-wallisellen-1070171586/ (in the description it says it is from the ...
Paolo, I don't know the make/model of your bike, but it seems clearly to be a standard design using standard components from perhaps the mid 20th century. For example Sturmy-Archer was famous for its 3-speed hub shifting system (like the one on your bike). Here's a brief history: https://www.sheldonbrown.com/sturmey-archer.html#history
What level of ...
Start by checking the hardened bearing surfaces on the inside of the wheel's hub. If they're not smooth under all the grime then its generally not economic to proceed.
Otherwise, you can do this.
Tools you will need to buy or borrow:
a freehub removal tool
two cone spanners of a size to fit your new cones so probably 15mm but other sizes are possible. You ...
If the cones are pitted, the bearing surfaces inside the hub shell may well also be damaged. As the rim is not particularly valuable, your local bike shop may be able to sell you a complete replacement rear wheel to suit the screw-on 6-speed block you have.
If you really wanted to only replace the axle, by 1990 I would expect a non-vintage hub to be using ...
I think this answers your question.
Your headbadge is slightly different, probably older.
See also https://en.m.wikipedia.org/wiki/Sunbeam_Cycles