The one concern I have is the exhaust valves, they look to be welded due heat discoloration where the head and stem meet and could have been welded? Can someone confirm? Just want to make sure they are one piece valves. My thought is if they are a two piece welded valve I will/should replace them?
A good quality two piece valve is fine.
The stock valves fail because the heads are brittle … not because they are made from two pieces. When valves fail they crack and separate from the stem below the weld, not at the weld. Most valves in the world are made from two pieces, but they don't fail.