If you can spend the cash Mitsubishi mini splits will last forever.
Most of them are pre-charged for ~25 ft line sets so as long as you are in that range it's easy with some patience.
Vacuum pump, flaring tool, tube bender, micron gauge and a set of hvac gauges.
If you can get a small tank of nitrogen for a leakdown it would be preferable. (im a certified hvac tech, most of them are not complicated)
