Hi @SoCalFMDude
The PT100 type of thermocouple is very popular for industrial temperature measurement.
You will also need a PT100 amplifier to handle the signal from the sensor and make it easily readable. The amplifier will also likely have calibration points that you will want to set to get your +/- 1% which is a pretty tight spec at 300F.
To really get that kind of accuracy you will need to calibrate each sensor at a couple of known temperatures such as ice bath, boiling water, etc. Another approach to calibration might be a lab hot plate and a higher precision lab thermometer if you have them.
That display looks OK, but I would choose one that you know will work based on postings here in the forum. It is hard for us to know what your constraints are for the display without more details.
There are many choices for the database part as well. You should read up on webhooks in the doc since that will likely be the key to getting your data from the Particle cloud to your database.