I have data on a 68 Yenko, April car, with the POP (MV) and the original engine it left Yenko with, which is a CE block.
Also, Fran Preve has dug into the Tonawanda records and determined MV's were 396's.
Now, there could have been a running change during the year, but re-using an existing engine code would be unusual.
One other thing: if Chevy was installing 427's into cars in 68, then what held up the 69 COPO's until January of 69?
Just more fodder for discussion.
Kurt S
CRG -
www.camaros.org