Yes, they're the same diameter, although most bullets for the .45 ACP are 230 gr. or 200 gr, whereas the traditional .45 Colt bullet was 250 or 255.
The Bullet Barn here in BC does good stuff, although the shipping to Ontario might be a bit steep.
As I'm guessing you're new to this, it might be worth mentioning that although the traditional .45 revolvers such as the Uberti Cattleman etc. are "six-shooters", usually they are only loaded with 5 rounds since when the hammer is down, it will rest on a live cartridge. This is not such a big deal when you're shooting at the range (alas, the only place you can shoot dastardly restricted firearms!) but for carrying, loading all six cylinders was a no-no as a bump on the hammer risked setting off the round underneath it. Newer designs such as the Ruger Blackhawk have a frame-mounted firing pin with a "transfer bar", a thin steel bar that rises up as the gun is cocked and remains in place when the hammer drops, thus transferring the blow of the hammer to the firing pin. It then retracts out of the way. Some double-action revolvers achieve the same thing by having a rebounding hammer that resets after the trigger comes forward and keeps the hammer away from the firing pin.
BTW, I just came across this webpage:
www.genitron.com/Basics/Revolver/P2Revolver.html which might be informative.
x2 on getting the Keith book on sixguns. It's one of the classics, although it isn't cheap. If you don't know about Elmer Keith, do a google search. One of the great gunwriter icons of the 20th c.

Stuart