Hello Scotty,  in 1937 most countries in the West met to set out
a standard tuning pitch.  They agreed on A=435 Hz at [air temperature]
15 degrees Celsius and it is the only pitch standard ever ratified.
This is very close to A=440 Hz at 20 degrees C.  Many European
instruments use A=435 but the USA is a different matter.

Never pull up strings to A=440, Grotrian Steinweg said it introduces
six tons of extra strain over A=435.  Letting strings back down almost
always results in variables that are difficult to erase.

If you look at pipework, look at the bass pipes: the stoppers should be
close to the end.  Although they may be slightly out, you can usually
get a reading that is close to the fundamental pitch.

The other danger is increased bellows pressure, commonly done to
increase volume, which usually results in the pipes giving out the
wrong partials and harmonics.  Try altering the bellows pressure until
the pipe speaks sweetly and you will not be too far out.  Hope this
helps a bit.

Regards,
John Harrold