I don't have a link to point you to as I read this in several old poultry manuals. There was once an Australorp (in Australia, not the U.S.) that laid 364 eggs in 365 days. Professor Dryden in the early twentieth century bred a White Leghorn hen that as I recall laid a perfect 365 eggs in 365 days. These may have been bettered in the decades since.
You can still find high producing White Leghorns easily. High producing brown egg layers are now almost entirely the province of hybrids. I'd be delighted to find any brown egg layer breed that isn't a hybrid that can consistently lay 250 eggs a year in their first year. No idea where to go to get them though.