thanx for the info....the one original salvageable barrel from the engine and one that I purchased are the same part..however I see the original one is marked as a B , and although it was to be a B, by part # as well, the one I bought has turned out to be marked with an A..I have brand new OEM unmarked pistons to be installed. The original barrel's chrome inside diameter surface is clean and unmarked , the one I have managed to get so far appears to have a slight crack like mark between the exhaust ports...I am concerned about this and also about the clearances ...Unless I am mistaken the A B C barrels are identified as such for size and clearance purposes...and so too this would be for the B no mark and D pistons ...Is there someone who has experience in what the sizes and corresponding clearance are , and what tolerances I could deem acceptable or get away with without re chroming the barrels?...If I have to have the chrome plating in the barrels restored, does anyone have a recommendation as to who is the best suited for the job. and the costs...here it costs approximately 300...to 400 Can dollars to do each one !