bolting on X-heads to my 340, can i use my exhaust manifolds?

I have looked at the copper just never used them. The silver graphite with the metal inner core. They don't leak and i have reused them a couple of times without issue. I still dont throw the old ones away, just in case I need an emergency one! Also is that an air gap intake?
The one that is on there now I believe so… It is rated for 1500–5000 RPM power band… I want power band from idle-5000 rpm... so I picked up a weiand