as per my Toyota repair manual for my 84
idle: more than 0.3kg/square cm(4.3psi, 29kPa)
at 3000rpm: 2.5-5.0kg/square cm(36-71psi, 245-490kPa)
This being said, if i had 4.3psi at idle i would be going thru the motor, my 84 with 225,000(fresh motor 40,000 ago) runs 20 plus at idle,and pegs the meter at 3500(this with 20w50 castrol) I run 10w40 in the winter and have about 10% less pressure.
And now... the low tech reply!
On my guage, I normally see the oil pressure guage to the left of center at idle, close to the middle, but definitely on the left of the center mark. My car does have 228,600 miles on it with the original pistons and rings though.