To start, a 340 is considered a "small" block engine (as small as 273) and a 440 is considered a "big" block. All engines have great performance potential. However, not all engines are available from the factory in every body style. If you are considering a Barracuda, Dart, Valiant, these are called-"A" bodies, a smaller car. The most common engines found in these cars are the slant 6, a small V8 from 273 to 360, with some rare ones with 383,440,426 engines. If you are considering a mid-sized car like a Roadrunner, these are referred to as "B"bodies and include Roadrunner, GTX and Satilite. These cars could come with slant 6, V8's from 318 to 360, with some rarer ones having 383, 440, 426. On any car with a larger, "big block" engine be prepared to pay a premium price as these are rare and highly desired. For a small block motor to even approach the power levels of a big block requires much more than "tuning"- major engine components need to be replaced. At your skill level you should consider buying as much car that you can afford and just enjoy driving it.
