When these engines (194,230,250,292) came out in 1963 they were called "thin wall castings" so it might be wise to have the cylinder walls sonic tested. We raced with a 292 powered circle track car that was very competitive but had a problem with #1 cylinder fracturing. When Mercury Marine started to use them in boats they corrected this problem. A sonic test is cheap and might reveal a thin spot in in just one cylinder which could be sleeved and that is less expensive than doing all six.
