If all this seems rather dictatorial, there are alternatives on the piston front as a choice between flat-top or dished (26cc) variants is available. Paired with heads having 62cc chambers, the former would result in around 11.04:1 compression on the 427, while the dished slugs would yield about 9.5:1. In either case, the piston manufacturer is Mahle, with 1.245-inch compression height, utilizing a common 1.5mm/1.5mm/3mm ring package. Dart will work with you or your engine builder on desired compression. For our subject build, Dart opted to use the flat-top pistons, but opened up the accompanying cylinder heads' combustion chambers to 65cc for 10.5:1 compression.