Where should my oil pressure be?

I want to know if my car has good oil pressure. In my house, we have three fox mustangs. Two are 91's and one is an 89. The two 91's read somewhere around the "O" and "R" in the work "NORMAL." My 89 usually reads lower, between the "M" and "A." It is usually closer to the "A." I just want to know if I have anything to worry about on the 89. Is this still an OK reading? The two 91's have about 80k miles on them and the 89 has exactly 100k on it. I have noticed many similarities between the two 91's, being that they are from the same year. Just wondering if maybe the 89's had similarities, like a lower oil pressure reading on the gauge. I know that the oil pressure gauge in the 89 in measured from 0-100psi and the gauge in the 91's is measured from L-H.

I just took the car out and when I got back I went to check the dipstick as soon as I shut the car off to see if a good amount of oil was still in the motor. I know the oil is supposed to be hot, but the dipstick had steam coming off it. Is that normal too? Again, I just turned the car off.