I have read this post and I am confused about the strategy. I also know the Kaiser engine and transmission history.
You have a really nice car; maybe I am missing something, I don't know.
By putting any V-8 in a 1949 Kaiser; is certainly going to change the balance of the car. When I say balance, I am using a broad term. The Engine change would alter the car, and it would be a modified. In some shows it would have to be put in a modified class.
The picture of the car, you referenced, in Hemmings; is a modified car. Not only has the engine been changed; but it surely looks more modern, by the way it sets. So probably, brakes, suspension, and other systems were altered. If you are looking to be classified as modified, sure do the change.
Oh sure we have built street rods, and many other types of cars, for our own use and customers; but they ended up with a modified car. I guess, I saying your car is too nice to go through that.
Then selling it, as a modified all the "original", buyers would be turned off.
Maybe do a bit more research before; jumping off the edge.