340 X Head Valve Options

3rd pic looks like your chambers are about an inch deep! Its only the head gasket that gives that effect. The "double" springs you mention are probably just spring dampers , every 340 head I have seen has had them. Exhausts get the hardened seats, intake is not an issue. Have you looked into 7mm magnum valves? Do they make a 2.02? Or even back cut Manley valves?