Bb LP is not A=440Hz. I've measured both flutes and clarinets and Bb LP is diapason normale, the French 1859 standard, which is A 435 Hz.
It's my theory that Bb LP plays flat and with compromised intonation at 440 because shortening the barrel is like attempting to tune a guitar by leaving the strings at the same tensions and moving the bridge. Even the best compromise will have part of the frets playing flat and others sharp. So tension is adjusted. In wind instruments, the only way to change the "tension" in the air column is to change the air temperature.
I became curious about pitch inflation so I obtained 3 Bettoney flutes to compare, built within about 5 years around the time of the adoption of 440, officially 1920 by US gov, 1917 by the musicians' union.
One flute was an HP, another LP, and the third a 440. All Bettoney, different lengths and different tone hole placements, interchangeable heads.
I've also been looking at the development of th Penzel Mueller clarinets during the post WW1 era and 1930. These are not completely 440 until the LP designation disappears.
A pitch standard can be enacted suddenly, but that doesn't re-tune all the pianos in orchestral use. Tuning a diapason normale piano to 440 is so much increased tension that it damaged many pianos of that period. It probably took 25-30 years for the new standard to be completely adopted in practical use.
An LP clarinet with an original barrel is likely your best bet for working at 432. Temperature has a noticeable effect on the pitch as well. If you play a wind instrument in a cooler room, it willl play flat. It will be sharp in a warmer room.
An A Hindley (Nottingham circa 1875) clarinet that I recently completed is quite plausibly built to A= 430 or lower. There are no marks for pitch or key, so I'm pretty sure it is a Bb and not a high pitch A. In France and the USA, it appears that orchestras mostly used diapason normale standard at 435. In other countries, the standard appears to have varied from town to town.
The designs for guitars likely went unchanged when the pitch standard changed. String gauge and tension could address the situation to a degree.
Better guitars are built with custom dimensioned parts that are tuned for resonance at particular pitches. It's plausible that most 20th C. Guitars were built to dimensions derived at A=435, and thus are more resonant when tuned a little flat.
Regarding the debate concerning the various standards;- no "standard" can result in more responsive or better built instruments if it is a moving target. Far more wind instruments have been built to the 440 standard than any other standard, and among those are many instruments from a period of superior materials as well as superior manufacturing and sufficiently advanced tuning technology. Any attempt to move the standard from 440 should be resisted.
If one wishes to play at 432, I understand that and in fact, I also frequently perform at 435-430, depending on the weather. There is no shortage of LP instruments, and that is what I play at least half the time.
