cylinder works big bore kit?

[ridehonda400ex]

Hey guys, ive been gone for a while. I got a yz250f over the weekend and im in the process of rebuilding it. I got it all apart and the cylinder has some marks but still good cross hatch. Im looking at the cylinder works big bore to make it a 270. could i get some reviews on these?

[01boneless]

dont know about dirt bikes but they are great cylinders on the 450r. there pistons are vertex brand, usaly low compression. mixed feelings on the piston some like vertex some dont.