Actually, there are bunches of new aluminum 235 pistons on ebay, in all oversizes, at pretty reasonable prices. A standard bore 235 piston will work in a 216, just bore it 1/16" oversize (.0625"). The wrist pin diameter and compression height are the same. As Panic mentioned, the dome is pretty shallow, so the overbore will compensate for the lack of a dome, somewhat. A bored-out 216 with 235 pistons comes out at 224 cubic inches.
Jerry
