I just bought a 73 Dart Sport with a slat six in it. I was wondering whether i should switch it out with a 340 or something bigger for the horsepower gains. What would be my best bet for a good powerful swap?

 

Either a 340 or 360 should provide plenty of power for you. The 340s are getting a little pricier and harder to find, so if the budget is a concern, a 360 would be the way to go. It can be built to run as strong as a 340 as well.

 

The 360 is your best bet, it is more powerful than the 340 although some might argue it, the facts remain. And as mentioned the 340's are getting pricey and hard to come by. You can get more 360's than you could ever use for near nothing since they made them up through the late 90's and you can build them up more or get a crate engine version with 395 horsepower for a pretty penny.