Biermann, the engine in your truck now is likely a plane-Jane 216 and either original or pretty much exactly what it originally had
Let us know the stamping by the distributor if you can clean it off enough
As mentioned above your gmc did originally come with the Chevy engine so you have many sources for replacements or parts found all over the prairies.
It is not easy and not original to swap it out for a gmc engine like the USA version of the truck
The Canadian gmc is built on the same Chevy frame so the engine mount points and radiator surrounds don’t work out without modifications
-s
