This is my fault for not paying attention while teardown. I have an 86 Chevy 292. It has pistons with a D-shaped dished top. There are no notches on the pistons, but there is an "F" embossed on either side of the wrist pin on one side of the piston. Is that the front, or do I orient via the D shaped top, and if so which way should it face? Thanks.