Hey guys, im rebuilding my 04 kx250f top and bottom end. I went with a brand new 07 kx250f head cams buckets etc, steel valves, 270 big bore kit, and hot rods crank, bearings and seals, and oversized rads with silicone hoses. Im hopin all this will leave my 04 more reliable and give it a little more power. I have a few questions about the rebuild. First being with a brand new head and valves do you have to have the valve seats cut for the valves, or can I just throw the new valves into the new head and go from there. Second is are the cam chain guides ok to reuse or should I go for new ones? And last question being how hard is a crank/ bearing, seal replacement? My local shop wants 430 bucks for the job and thats only the price provided I supply the crank, bearings, seals, gaskets. I would like to avoid paying that provided its not too much of a pain to do it my self. Thanks in advance for the help!