Hi,
I'd probably skip dividing the accumulated result by 10 in order to keep the resolution as long as possible.
It's not perfect but perhaps something like this might work:
Code:
newtapsetting = (dist ** 3060) - 42
IF newtapsetting > 127 THEN newtapsetting = 127
This will give you a newtapsetting ranging from 0-127 for a dist value ranging from 920-3640. (At least I think it will....)

/Henrik.