Malcom,
The radiator is not correct for a 3A.
The '49 3A will have the bottom mount radiator. (At least mine and Macs do) , so you will see the tabs on the crossmember if it's early 3A.
There are no bumper gussets, and the front engine mount plate has the dog ear facing forward on the driver side, so the frame is 3A.
The grill is 3A.
The engine has ridges on the head, so it could be a 3A engine. Do you have the serial # on the water pump boss?
From your photos, I say you have an early 3A with the wrong radiator.
Tim