The mains that are really scarce are the ones for 54 and early 55 235 engines, the ones with the locating dowel pins in the upper bearing shells. That's particularly true for the .030 undersize bearings. There is a way to make the later type bearings for late 55 through 62 engines fit by doing a little simple surgery on the block with a die grinder or a Dremel tool. Drop me a PM and I can outline the procedure for you or your machinist. The later model bearings with the locator tab for the upper bearing shell at the parting line between the block and cap are much more plentiful and less expensive than the earlier type bearings.
Jerry

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