Howdy Matt:
Is the Holley of of the 144 or the 170?
In '61 model year the 144 carb would be a 1908, rated at 130 cfm. In 1960 the carb would be a 1904 rated the same 130 cfm.
What year is the 170 engine? A 1904 for a 170 from the 1960 model year is rated at 150 cfm. The 1961 1908 model is rated at 150 cfm too. I'd certainly use a 170 carb on the 170 engine.
There is very little to differentiate between the 1904 and the 1908 models- a sligntly smaller bore in the later 1908 model. Both came with either glass or zinc float bowls.
While these little gem carbs are getting scarcer, they can still be had through rebuilt lines. They are also getting pricier as their coolness factor rises. They are about as simple a carb as you can find and quite durable.
Hope that helps you.
Adios, David