Non Jet valve head on import bottom end?

[Will]

I opened up my spare engine and the engine in the car and found the previous owner has probably put the original non jet valve head onto the imported engine. Does anyone know if this will affect the cam timing if setup with the timing marks? ie. Does the import engine have slightly different timing marks compared to the local one?

The 'hybrid' engine has been running, but it wanted lots of advance without any sign of pinging. Symptoms that very much felt like incorrect cam timing.

I read on the old forum that the cam in the jet-valve engine is more conservative. Is there any way I can tell which cam is which just by looking at them (without having to remove if possible).