I pulled a couple of valves, did some measuring, and found some discrepancy. The valve with actual CONTACT with the rocker rail measured .25" groove to tip. The valve WITHOUT contact, but very close measures .29". I don't know if the previous owner swapped some valves or ground the tip down. It looks as if some grinding was done. Tip of valve has machine marks on it. Do I file off rocker rails & install guide plates, or buy new/ longer valves?