My 69 had the 170. I run 33 12.5 15s on it. It was bad weak. Acceleration was pretty non existent. In 4 wheel high, it struggled to pull itself on take off. I dropped in a 200, its still pretty weak but a little better. I found a 250 dirt cheap and a 4 speed, it may go in next. At some point, I should just realize I need to drop in a 302 to be able to drive over 65 on the highway.