Intake/Exhaust manifold questions

[Praxiss454]

Rebuilding my 230, and I have the manifolds off. They are still connected together, as I was advised by the machine shop as well as an experienced buddy not to separate them. I have a few questions I was hoping someone here could help shed some light onto.

1. Why shouldn't I separate them? I'd like to blast them, paint them, and replace the old gasket between them. I could paint them together as-is I suppose. Would just like to understand the reasoning for not disconnecting them.

2. The heat riser spring is long gone. The valve rotates, perhaps not as smoothly as it once did but rotates none-the-less. It gets cool here (SF Bay area) but not ice cold. Thinking of leaving it without a spring. Dumb idea? I guess I could get the spring.



3. On the intake manifold, there is a pin held in place with a cotter pin on the end. It rotates freely. I've cleaned mine up a bit. But I don't know what it's for. There was a small piece of metal on one end, like the end of a spring that might be connected to the carb or throttle, but whatever it was, it broke. What's it for? What's the replacement spring called?



4. These studs snapped off. They were pretty corroded anyway. I have them drilled out and re-tapped (3/8-16, hope that was right). Didn't have the forethought to measure them first, what is the right length? Anything special about them or just any threaded rod will do?



5. Same picture as #4 - my understanding is the only mating surface is the small chamfered ring. Do I need to do anything special to clean this up or get it to seal well on reassembly?

Thanks guys, feel like I'm in the final stretch here.