Need 1966 Dart GT Hypo Info

Not sure if I'm in the right forum for my question bu here goes.

I have a chance to buy a very nice low mileage (46k) 1966 Dodge Dart GT, 273 High Performance (solid lifter car), automatic, numbers matching, factory a/c, manual disc brakes, southern car.
Questions: 1- how rare is the 273 High Performance.
2- what is the HP as I am finding outputs of 230 hp and 275 hp on line. Not
clear as they refer to the D/Dart drag cars built that year (50 or so).
3- Any production numbers