[flatford8]

How full was the radiator? It doesn’t need to be up to the filler neck. When you shut the motor down, especially inside a building, residual heat can cause the expansion you experienced. Don’t refill all the way and try what you just did a few times to see if it stops puking.
There is a very experienced poster on here who has forgotten more than I’ll ever live long enough to learn about these vehicles, insists the rad must be full to the top,but since I was old to enough to reach the radiator, I was taught to not fill all the way up. Leave room for expansion......Mark
P.S.....can we see some more pictures of your car....thanks!