oil pressure and different weight oils

Shitt, back in the old days, the low class stock eliminator cars, ran 3 qts of 5 weight. At idle would hardly move the gauge, and at 5,000 rpm would be lucky to get 30lbs. Of course the engines would have the bearings checked every week.
Granted I only run a slant six, but I turn it 7,000 rpm, and am making close to 400 ftlbs of torque at 2900rpm, and I have about 25-30 lbs at 1000 rpm, and 50 lbs from 2,000 rpm up.
PS: 10w-30 oil