Smith & Wesson .45/.455 bore diameters

I have a Smith & Wesson Second Model Hand Ejector (‘HE2’) made for the British around 1916. When it was imported back to the U.S. its cylinder was shaved to accept .45 ACP in moon- or half-moon clips and the ‘.455’ stamp on the barrel was altered by obliterating the last ‘5’ and stamping ‘AR’ under it.

S&W offers the Model 22 1917 in their Classic line. Ninety years ago, the M1917 was made in .45 ACP for the U.S. Army. The new guns are also made in .45 ACP.

Question: Did the U.S. M1917 and the British HE2 have the same bore diameter? That is, were the British guns’ barrels manufactured with their own bore diameter; or did they just use the same barrels as the M1917 but with British markings?

Question 2: A short email from S&W said that the new Classic barrels would not ‘fit’ on my HE2. Did they change the threads? Eliminate the pin? Is it the bore (which shouldn’t matter if I’m shooting the same ammo)? They haven’t answered my follow-up email.