Was S&W consistent with the bore diameter on the older .44's?
I plan to start reloading for mine (1925 Vintage) and would like to know what size cast bullets to use. Just cleaned up the barrel and
I don't want to be beating down lead balls if I don't have to.

Groove diameter runs generally .430-.431". What is critical is cylinder throat diameter relative to the barrel groove diameter. You don't need to know barrel dimensions, just drive a slug down the barrel and then see if the slug fits through the throats with little or no resistance. This allows you to know bullets fired through the cylinder will not be sized under groove diameter by a tight throat. This is usually not an issue on the early guns as they have a reputation as excellent shooters.

The second thing is to slug the cylinder throats and order cast bullets .001" larger than the throats.

Or, you can take the lazy way out and simply order your bullets in .431-.432" and use them. You may have to look around, not all vendors of cast bullets will size to your specification!