you should check what the cylinder bore measures, high and low....and try to determine what your current piston to cylinder wall clearances are, along with your current ring end gap, before buying a top end kit, just yet.
I know this a budget build, but if the clearances are too great, there's a chance you may have to re-plate the cylinder....if you can't get a correct size from ProX...though I'm pretty sure ProX go in 1/2mm increments, so there's also chance you may "not" have to do anything with the cylinder.