I remember the boiler. It's a big cast iron unit with front swing doors, that was capable of burning coal and wood and sometimes was converted to gas. Hugely inefficient!
You are right about the American Standard, the Standard Sanitary & Dominion Radiator Limited company and foundry that produced boilers, radiators, drains and other items later became AS.
Finding info will be difficult, although not much to know as it was a simple unit, anything added such as a gas train was most likely aftermarket anyways.