It will work with your stock head and valves. The item "04 05 TRX450R TRX 450R 97 CP 500cc Big Bore Hot Rods Stroker Motor Rebuild Kit" is in sale since Friday, May 17, 2019. This item is in the category "eBay Motors\Parts & Accessories\ATV, Side-by-Side & UTV Parts & Accessories\Engines & Components". The seller is "azquadparts" and is located in Gilbert, Arizona. This item can be shipped worldwide.