Originally Posted by fast68plymouth
I’m not sure which combo the “543” is.

4.375 x 4.500 is 541.2
4.380 x 4.500 is 542.4
4.500 x 4.250 is 540.7
4.440 x 4.375 is 541.9


Our 543 kit is a 4.500 stroke x 4.380" bore, which equals 542.43 cubic inches. We offer pistons for that kit in .060" over, so we usually rate the cubic inches at the largest available bore size. And we did round up by .57 hundredths of a cubic inch.