The friction steering damper will work fine for that bike at its speeds. I have run at Maxton with a 1954 Parilla 175 4 stroke with a similar damper. Just remember to adjust it tighter than you would for a roadrace but not so tight that it won't allow you to do that right hand turn at the end....
As others have said, though the rules don't require it for your class, it feels much more comfortable with the damper cranked on than without a damper which I also did at Maxton with my Montesa Trials bike for 3 runs.
As for your other question, the M/BG 175/4 record is indeed open at Maxton for your Honda 160. So, make it to the finish line and get a record! But the problem will be that you will not be satisfied with that one, and you will want more and more and more! Then we will have you right where we want you- hooked. I am a fellow Honda rider (250cc) and there are not many of us at Maxton. Come say hi.