I'm looking for a high temp switch for my Jacuzzi Venterra tub. I've found some switches on the internet but I haven't been able to fine one with the same dimensions, i.e bulb length, capillary length. How important is it to get an exact match? Also, I haven't seen the max temp rating listed for any of these, is there a standard?

a shorted bulb lenght is just fine. A smaller diameter will work, but wont be quite as accurate, but still probably "close enough for government work"

Typical temp rating is 121 degrees