273ci--a keeper in my 64 Dart GT 4-speed?

I love 273s! The two barrel 273 is just a nice running motor. But it would be a bit more affordable to put in a nice 318 and the extra displacement gets more torque at low rpms where it's noticeable. If you go for even more torque & power with say a 360 then you'll start getting into upgrading other items like the rear axle.
So I say 318.