I understand why people go w/ a 347 especially if they already own the car/engine. Because of the taller deck a 351 needs different intake and exhaust headers so they would be an additional expense. But if starting w/ nothing, a 351 costs no more than a 302. And, if you are satisfied w/ about 350 cubes, you can use the stock 351 internals, vs a stroker kit to get from a 302 to 347.