Which is better a 305 engine or a 350 engine?

it just depends, the smaller the cubic inch size, the less oil drag, there for more horsepower, but the thing you have to look at is liter size, the bigger the liter size the more horsepower, but the more power and the more strain on its self, so you might get a 25k to 50k more miles out of a smaller liter size but you sacrifice power. 305 and 350 is chevy so its either 5 liters or 5.7 liters, .7 liters more makes a huge difference in power, but then you have gas miledge to take into consideration. so it ultimately depends on what you want out of a car.

-350, the 305 wasn't really a go motor(that's why it hasn't stayed in production like the 350). The 305 had problems with FI and had poor performance. If it is for a replacement motor a 350 for the same price has 75hp/76lb-ft more. 290/326 vs. 210/250 for a long block $2200.