found bad ground at gauge, t stat ? now

[subman60]

Well i found that i have a bad ground at the gauge cluster which was causing the temp gauge to read above 120c. That good news but the gauge still reads just over 100c. When replaced the thermostat I got it from a local NAPA store instead of a MB supplier. I checked it before installing it and it started opening at a water temp just above 80c and didn't fully open until about 93c. Does this sound about right? Also i read there should be an arrow which when installed should point up. Neither the stat i took out or the one i put in had such an arrow. Should I pull this stat and get one elsewhere, if i can use this stat without the arrow does the position of it matter, (I do know which ends point towards block and radiator. Pointing up towards hood is my question)?

Thanks again,
mark