[NiHaoMike]

Then you'll certainly want a R410a compressor. Oversize the condenser and evaporator as that will get you better efficiency and allow it to more easily deal with high evaporating temperatures. Then add in a high pressure cutout (set for about 350-400 PSI), a low pressure cutout (set for about 50 PSI), and a delay on break timer (5 minutes or more, preferably 15 minutes or so). Use an oversized liquid line filter drier with the outlet facing down, as that will be your liquid line receiver. The TXV should be R22 and matched to the compressor, internal or external equalization depends on how restrictive the evaporator is. (A "snake" probably isn't restrictive enough to use external equalization unless it has multiple loops and a distributor.)

The thermal inertia of your system is so high that you probably won't see much real advantage of using a VFD. Use a "minimum time" method of control, where the controller turns on the compressor and pumps and leaves it on for a minimum of say 20 minutes (unless manually switched off or tripped on a fault), then turn it off when the required variable is met. Then it waits say another 20 minutes before it lets it come on again. (The latter is a delay on break but most delay on break modules won't let you set them that high.)