I am sorry you lost that R-12.... that is one advantage of doing the actual installing at a place that has a recovery unit....
Since the trend is still in our favor here in Texas... I suggest you stick with the R-12 .... after you fix your leak of course...
Did you use any ' sealer' on those seals ? There is a 'thicker' oil used to wipe on the orings and seals... it is the same as what goes inside ( there is one for each refrigerant)... but just thicker is what I have been told... can't think of the name... senior moment...
Which places leaked ? Why did they leak ?
Which color orings did you use ?