I agree that the only thing that might make that clearance too shallow are the actual motor mounts. If you're using a dual action AC pump, there is not a lot of clearance on the Henry J six. The cars were originally equipped with Carter pumps and they are not as tall and fit nicely. I had an AC on my '52 J for a few years. It worked fine for fuel but, just as all AC pumps do, it would sling a bit of oil out the breather holes. As soon as I found a Carter, I replaced it.