Firestone continued to offer a rope start in 1949, model 133-486. Model # suggests they were leftover 1948 motors.
It looks like all the singles were 2-1/8" bore X 1-3/4" stroke and rated at 4000 RPM. I don’t know what they did to get more ponies.
AHA! The 3.6 non-shift used cylinder head # 470-1883, The 4hp shift used cylinder head # 491-1883. Both 6 bolt, but probably higher compression.