To be sure of the chamber size it would be a good idea to cc them, you never know what was done to them in the past. The casting number will get you close to what they were when manufactured. I think you're close with the numbers you stated with the dished pistons.
1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy
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