My P20 has a slight offset at the BB with the 73 mm shell and I am using a 110mm spindle with a modified triple that has a 40/50/53 crank. I designed my rear triangle with a slight offset to give the bike a better chainline with the triple where I spend a lot of time in the 50 and 53 tooth chain ring and much less time in the 40 tooth granny.

The offset on the Raleigh bb was done to give a better chainline with an AW hub so if you reface the bottom bracket you have to keep this in mind.

Remember that the Raleigh Twenty has a bottom bracket that should be 76 but may vary by .5 - 1 mm and installing a 73mm cartridge requires refacing of the bottom bracket shell to 73mm.