That scope should be perfect for your task. A 4x scope is good enough for almost any hunting situation in BC. I have only taken a shot at game with my scope cranked above 4x on one occasion, and that was when I had time to lie down with my bipod, use my laser rangefinder and take the perfect shot across a canyon with a tuned-up .300 Winchester Magnum. On all other occasions, I've shot with my scope sitting at around 4x (or even lower).
As to the suitability of the scope itself, if it is an older Bushnell, it is almost certainly a centerfire scope. Here is how you find out: 1) if the tube is one inch in diameter (as opposed to 3/4 inch), it is almost certainly a centerfire scope. 2) if the eye relief is 3 inches or more, it is a centerfire scope (rimfire scopes generally have eye relief of an inch or so). Just look through the scope. If you get a full, perfect picture with the scope about 3 inches from your eye, you are good to go.
Final note: look to see if it says Made in Japan. If so, you definitely have a winner. Those old Japanese Bushnells were very good quality and still work great today (I have a couple).
If the scope passes these tests, take your buddy up on the offer!