Yes we are talking a 4 barrel
289's in various performance levels were available from Ford with horsepower ratings from as low as 195 up to the Carrol Shelby tuned 289 Hi po's in the Shelby cars that were rated at 306 horsepower IIRC. A 289 HiPo was rated at 271 horsepower.
There is nothing significantly different between a 289 and a 302/5.0 other than balance issues that must be observed. A 5.0 with good heads and the right cam can easily duplicate the 289 Hi po numbers across the board. I would venture to guess that if built with identical components the 302/5.0 would make virtually the same power as the 289 with a tad more torque and maximum power coming just a few RPM lower than the shorter stroked 289, but for all intensive performance purposes the engines are identical.
structurally, the 302 blocks have longer bores and support the pistons a bit more and MAY have a little longer longevity under hard usage. Again, in reality, you would be hard pressed to actually see any benefit of one over the other.
210 horsepower doesn't seem like a lot by today's modern standards, but it is more than enough to overwhelm your 1966 chassis.
You can get more with a more aggressive cam, better heads, headers, improved ignition etc, but you will quickly discover that your car can't use the horsepower without suspension modifications.
Enjoy your car and don't worry about "numbers"