Have just stripped an old raleigh gents bike down for restoration. It’s a 50’s beast with rod brakes.
The intention was to fit a new bb and crankset to do away with the original cotterpin job. However, the drive side of the frames bb shell is capped and the bb is extracted from the non-drive side.
Question is, does this cap unscrew or can it be driven-out? therefore, a more modern bb will screw-in as a replacement.
It’s actually the same as a Chopper I did recently, but I wanted the original crankset on that so left as-was.
Cheers for any help

Most old style are the same as normal. A left hand thread on the drive side, they are round steel cups, the same diameter as the steel frame but with two large flats on to get a spanner on. Perhaps your lbs may have the spanner in the tool box, it will help a load as they are very very tight.
Older ones may have had lots of paint on top to make it look part of the frame,
So yes you should be able to fit a newer square taper one, BUT older bb axels with cotter pins come in a multitude of lengths so it may be tuff getting it right first time. Some were mega long.

The drive side isn’t capped as such, but has a ‘fixed’ cup – there should be a flat on either side to remove it. They weren’t called fixed cups for nothing, and their removal from an old frame requires the strength of a gorilla and the patience of a saint. Bike shops used to use a fixed cup removal tool that clamps onto the cup so it can be turned (left hand thread)

Old Raleigh’s used to have non-standard BB threads as well – 26 TPI instead of 24 TPI.
As usual, Sheldon is the man with the info : sheldonbrown.com/raleigh26.html