you'll have to take the jugs to a machinist to do the bore/press work for the big bore. that will cost you just under $200, but while you're there and while the head is off you might as well have the machine shop do a port/polish, they'll probably only charge you another $100 or so. Oversize valves are not really produced yet, only custom orders. Mine were $250 and took 6-8 weeks to arrive.
