Other than the code..the block is nothing special. If you don't have the original block, no point on looking and paying a premium just for the code. With that..the heads are ordinary #16s found on any other 68 and command only what their condition is.
If it were me..and it was that important..cover up the code with paint.
You will not get any more for the car with a non original WQ block over say a WZ.
Si Vis Pacem Parabellum
1967 Starlight black PMD Engineering 400 Auto 1968 Alpine Blue 400 4 speed 1968 Verdoro Green 400 HO 4 speed 2013 1LE 2SS/RS Inferno Orange Camaro.
