If it’s the standard bore and looks like a UK cylinder then I would say it’s chromed.
The basic design idea, being as the cylinder had no sleeve, was for the rings to wear instead of the bore.
I have had some 8/1 engines (‘58/’59) that have been re-bored by Lister but I suspect this was probably done due to enthusiasm rather than need! Earlier (pre ‘50’s) engines (3/1, 5/1) often have wear at the top of the bore on the exhaust side but this is due to high hours and, I suspect, poor circulation in the water jacket.
Mark.