I read somewhere that a 10v block (like from a 1988 Quattro 2.3L I5) can not have a 20v head put on it (say from a 1990-1991 20V Coupe Quattro 2.3L I5). Is that true? The guy said that the valves would strike the pistons, but the bore as well as the stroke are the same. Do the pistons on a 20v block have reliefs in them? Lastly, can a 20v block be hooked up to a 10v drivetrain? Are the bellhousings the same or would I need a 20v bell. Thanks!