My advice would be to replace everything except the evap behind the dash. Get new pressure sensors w/ propper R134 calibrations, condenser, compressor, dryer, o-tube, lines and o-rings. Splurge and buy the AC-Delco o-rings for the back of the compressor. RockAuto has a great breakdown and choices for everything you need. You could even get everything purchased and installed DIY, but leave the evap open. take it to a shop and ask for an evap flush, evac/leak test and charge on the system. This way you dont have to buy any HVAC tools and you save the labor for part swapping.