well that was disappointing nobody could answer this question.
So I spent about 3-4 hours and got all the fittings and hooked it up to two different air compressors,
one with 0-30psi, and the other 10-100psi, and took measurements at different pressures.
The oil pressure sensor is the stock unit for a 1987 Chevy, this specific part number fits many chevy's 85-90's.
The resistance values had distinct steps, 20 different resistances were found.
I report on the steps as decreasing pressure, i.e. I put 100psi
and leaked it down, numbers are rounded.
You could pretend this is 0-80psi sensor where PSI = Resistance + 10, but it would be off a little.
PSI Resistance
90-100 107 (max)
80-90 95
75-80 90
70-75 86
65-70 82
62-65 79
60-62 75
56-60 72
52-55 68
50-54 65
48-50 61
45-48 58
41-44 55
39-41 50
35-39 45
25-30 41
21-25 36
20-21 32
15-19 27
11-15 24
5-10 20
0-5 0
Hope my results helps the next hapless person searching the web for the information.
And since you've read this, I reward you with a link to my video where I converted my tractor to a Distributerless Coil-On-Plug ignition
http://www.youtube.com/watch?v=imQkWVtHjRs
$44 in junkyard coils, $25 junkyard ignitor, a $12 isolated 12v-5v DCDC, $3 processor, $5 in opto's, and $2 hall-effect sensor.