If you have the rifle and the ammunition, see if the cartridges will fit the magazine and the boltface. If so, then all that would be needed is a chamber reaming.
If the head of the cartridge doesn't fit the boltface, it will have to be opened out.
There may not be many gunsmiths in Canada with a 7.5x55 reamer. Might be possible to buy the reamer yourself, and then have a 'smith do the reaming.
The reamer and gauges are likely going to cost over $300. The 'smith will likely charge you another couple of hundred. He is going to have to pull the barrel, set it up in the lathe, do the reaming and reassemble. $200 might be light.
Something else to consider - once you have shot off your G11, You will have a bin of Berdan rimed cases, and a rifle chambered for a less than common cartridge.