Just make sure you go with a 2.2 rod journal crank. Most 4.15 are 2.375 and in that case you may as well go 4.25. Nothing wrong with either stroke. A 4.15/2.2 would be almost no grinding. And you could still usea flat top piston depending on what head you use. some will say you may as well go 4.25 and they may be right. But to be honest 12 more cubes isn't going to do much. I personally think the longer the stroke the harder it is on the bottom end. But that's arguable. You probably won't go wrong either way.