340ci vs 360ci engine

If everything were the same, I'd go for the 340 as well, but I've never seen a usable 340 go for less than a premium price. 360's are cheap and plentiful and have 20 more cubes than the 340. There is no replacement for displacement. If performance truly is what matters, build a stroker motor using the 360 as a base. It won't be cheap.