Not sure why you'd only want to perform a vacuum test at the connection points you show on the picture, meaning, the evaporator only. Plumb up the whole system and then do the pressure test, preferably with nitrogen up to the system's working pressure (which is as high as 3-400 PSI on the high pressure side) and then some. That will be a far better test than just the 14.7 PSI of a vacuum test. You do through the working ports that will be part of the system to fill it up.
There are threads upon threads of AC work on this forum, including the epic one by Rob, the Hack Mechanic, not to mention his book on the subject. Consider studying this area of your work thoroughly as wasting precious R12 by having leaks once you charge the system can get expensive and frustrating.