Indeed, on engines this old it's hard to tell what's in there. I bought this '65 SC hoping for some good engine parts. It had 3 cast iron 86 mm cylinders with big domed pistons and one with a flat topped piston. The car was wrecked so hard both the engine and transmission cases were cracked.
Biral cylinders are as you described. They are tapered somewhat because if issues with thermal expansion. I think the head end is smaller in diameter than the case end - or vice-versa. Biral cylinders got such a bad reputation that you may find plain old cast iron cylinders in there.