To answer that question, you could use the longest LoRa range setting the Ra-02 @ 433Mhz can do reliably, bandwidth 62500hz, spreading factor 12.
An 8 byte packet would take circa 2 seconds to send at such long range settings, but with 4 stations and needing a reading once a minute thats OK. The line of sight range of those, workable, settings would be in the 850km+ range.
Thats a silly example maybe, but clearly you could send the data a bit faster and still get more range that you need.
You really have all the time in the World to collect such a small amount of data. Rather than have the sensors transmit at random and possibly collide and corrupt, just use the 'receiver' to poll the 'transmitters' for data when required.
The line in your code;
if (!LoRa.begin(433E6))
Sets up the LoRa device for 433Mhz, adjust as needed.