If I recall the Chevelle based cars in 1964 were badged "Acadian Beaumont". Just to make things really confusing!
I'll confuse you even more!
The Acadian was a Chevy II, but in 62-63 the Beaumont was a trim level on the Acadian.
By 1964 Acadian was a division that produced the Acadian (Chevy II) and the Beaumont (Chevelle). Same thing in '65.
By 1966 an Acadian was the Chevy II derivative only, and the Beaumont was the Chevelle derivative (Acadian no longer was mentioned when you were talking of a Beaumont).
The Beaumont stopped (I believe, but I might be wrong) in mid-'69 when the Pontiac Tempest / Lemans / GTO was sold regularly at Pontiac-Buick dealers in Canada; the Acadian was dropped mid-'71 when the Pontiac Ventura II was released. The original Ventura was a trim level on U.S. Catalinas from 1960-70 (Ventura 1, I guess you could say).
The Acadian, which was sold only in Canada, was built only in Lordstown Ohio starting with the '68 models. The Tempests that were built in Canada sometimes came with Chevy engine and sometimes came with Pontiac engines. I have heard some people claim that Canadian GTOs came with Chevy big blocks. Never! The GTO was built in Oshawa for 1970 only, and it was Pontiac power only! BTW there was only one Canadian-built GTO Judge with 455 power. One!
I know of a small number of GTOs that were sold new in Canada starting in 1965, but it still cost the buyer in excise tax. From 1969-on the GTO was normal in Canada. Built in U.S only (except '70).