fittings for a diy adsorption unit

I'm building an an experimental adsorption chiller, and am looking for some feedback on my hardware choices. It is not experimental in that it is new to the world, but just new to me. The working fluid will be methanol or ethanol.
The set up is simple. just two containers connected by copper tubing. (tubing will be at least 10 ft long, as it is the condenser coil). during evap, the line pressure will be below atmospheric. During regen it will be maybe 200 psi (a safe estimate).
The containers will have ball valves and threaded fittings, which will connect to the tubing with compression fittings. the tubing will have a pressure gauge (reading positive and negative pressure) and a valve brazed in. valve will be a needle valve to set evaporation rate.
The internet says soft copper is fine above 300 psi working pressure. does that sound right? will compression fittings hold vacuum and pressure all right? is there a better valve than a needle valve to use? I was going to buy a Pos/neg pressure guage from a local HVAC store. any issues i dont know about?
thanks for reading.

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