Chevy 427 engine installing into 69 camaro

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Need help installing a 427 engine into a 69 camaro.
should I use a long or short water pump ?.
This engine is stock. intake is also stock. So far the clutch and transmisson
is all installed the engine is in the car with the clutch linkage in place. I have a problem with the passenger side header it is touching the fire wall. This concerns me I don't know what to do about it the header manufacturer is Sanderson headers, can this be because I may not have the correct engine mounts and brackets How can I tell if the engine is in the right place.
The taller engine mount bracket is on the drivers side shorter on the passenger side is this correct.
also I have not alternator mounting brackets or pulleys