Cruise friendly low 12's with a 340 Dart

By dropping the milage, it can be done on 340 inches. but you'll need a lot more gear for low 12s. "in the 12s" is easy with a 340. If you want to have highway gearing (which for me means 3.23s with a 26" tire) and a reasonable stall speed then the best way I can think of is a 4" arm. You con't need big heads, or monster anything. The Performer intake would work, but it is small IMO. It can be done reasonably, be run on pump fuel. Doesnt need to turn rpms for efficiency, and bolts right in with existing cooling, fuel, an trans. The difference in streetability and drivability between a 12.90s car, and a 12.0s car, is very substantial with a 340. Like from pump gas and medium sized cam to mixed gas and more gear and convertor with a bigger cam. The diference between a 12.80s 416 and a 12.0s 416 is 10 degrees more in the camshaft and good tires. Most 4" engines I have built have traction issues in multi-use cars. To me, that's impressive. A basic 4" kit, a stage one port on your heads, or better yet LA version RPMS, and a cam with 250°@.050 or a little larger if iron heads are used, and you'll have an engine that idles under 800, runs a 2500 tight convertor, and runs mid 12s spinning partially into second with drag radials a 3.23s.