I am a DIY'er and I did it with the factory manuals. It took me about a week of PAINFUL work. If you enjoy working on cars, have the manuals and the time, it is "doable". If you don't, pay somebody to do it. It is expensive. Whatever you decide, get a copper core evaporator.
As far as the dye, that is how they found mine leak. Very reliable.
Do a search on the subject, right upper corner of this screen.

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J.H.
'86 300E