Did some research, not substantiated. Canadian engine numbers have 9 digits, no letters. Yours does have that. The symbol on front of heads is a 283/195 HP.(it is possible you have the 220hp) 1965 seems correct. The fact that you live in Canada and the engine says "Canada" sort of says it all. You will have to find a person who has Canadian archives or write to GM Canada. But how much more do you want to know? and why?
BLOCK NUMBERS:
1816887....63......283..........Made in "Canada", GMC HD truck
3731556....57......283..........Truck, Made in Canada
3884520....60-67...283..........Some marked "Made in Canada", 60cc chamber, also used by Studebaker
3884520....62-67...327..........Some marked "Made in Canada", 60cc chamber, also used by Studebaker
Your head no.
8785888, looked at all the numbers with a second dig 7 and 4th dig 5...nothing close.
Your block cast no. is known, as said.
