Bruce, my practical knowledge begins and ends with my engine. But quoting from “The Mighty Tin” article linked above...
The 4 cylinder block was constructed out of about 125 steel stamping. The pieces were held together by press fit, spot welds or crimping before brazing. The block is then copper brazed in a specially constructed 60 foot long furnace at 2060 degree F in a neutral atmosphere. The hardness of the alloy steel was controlled by the speed of cooling. The finished block weighs an extremely light 14 pounds.
I would suspect that if you heated the block enough to melt the brazing (2060 degrees?!?), then all you’d have holding it together would be the aforementioned crimps and spotwelds.
Some people - probably the Gorrells - have done cross sections with bandsaws and could tell you more about the internal construction.