I've attached multiple documents on bearings and bushings, perhaps one of these is helpful.
Not light reading. But there are is powerful data in these docs on the general principles.
These documents help me to understand why they get so much money for some bearings.
A internet search suggests that Norma merged with Hoffman in the 60s, and was likely later absorbed by a different manufacture.
I think you are going to need to begin calling some of the bearing distributors or manufactures.
You will need to find someone with a Norma cross reference document if you want to get the same construction.
Likely Linley chose that construction for a specific reason.
Another alternative (which I'm not recommending) is to get a precision bearing and have bearings ground to make up the difference is spacing.
This may take some prep work and a day of patient phone calls to get anywhere.
Please let us know what you discover. I suggest chasing the equivalent. If you decide not to purchase it due to price you might likely find something which will at least fit.
Daryl
MN