If it is the original Canadian CMP engine , it will have the earlier type valves, these have a slightly longer stem than the post 1941? USA type valves. Sometime around 1941 GM in the USA changed the setup and fitted the valve caps to the valves. But the Canadian CMP engines remained unchanged.
Somebody else , please chime in and point out any errors in my theory
Any 216 gasket set should fit OK , 1937 was the first year but I'm no expert as they say in the classics