273 Numbers Matching car. Should I rebuild or swap engine?

Thank you toolmanmike. I just found the site and this was my first post.... I am not a mechanic, so a lot of the posts are over my head. I was looking for a more general answer so I can call around for a mechanic and talk to him with a little knowledge and a direction from some of you A Body guys. This is a car I bought for my wife... I have a '70 CUDA 440 Six Pack and that engine I have researched as I have worked on it.... but this little 273 I know nothing about and just wondering what you guys who really know these motors have been doing to them. My wife wants to keep it numbers matching... I wanted to toss a Blue Print 360 in it... but I hear her on the original deal so we are going that route. I just want to give her a little more punch from the little motor. I am use to the Cuda, so the Dart just seems like my old 6 cyl Ford Maverick I had in high school would dust it. I realize the motor needs rebuilt, but can a 273 give you a little punch? Or is it just too small? I'll do some searching on the site as you suggested and I appreciate you replying. Have a good evening.
You can build them to be peppy but we have found there is really no magic bullet to make the 2 barrels a bunch better. More compression is needed along with a 4 barrel and a dual plane intake, headers and a free flowing exhaust. The camshaft is the tricky part. The 273's are easy to over cam and then you loose all your bottom end. Then you need a stall convertor and rear gears to make up for it.