First, a SB chevy race motor is a high-revving engine. A 22r(-e) is not. It is a low-rpm work engine. If you turn 7500 rpm's with one you're going to do more than wash a bearing out.
Second, once the oil pressure maxes out, that's it. the rest goes DIRECTLY back into the oil pan. Once the relief valve starts opening, you will get no considerable increase in pressure past that point.
Third, I would really like to see a non-existant cam bearing get "washed out". 22r(-e) heads do not use bearings on the cam journals, and since the head side is what all of the valvetrain pressure is against, and where the oil is supplied to the journal, maximum pressure early in the rpm range would be good (to create a hydraulic "cushion" for the cam to float on).
Last, the compression that the rod bearings are under (inside the rod, properly torqued) make spinning a bearing from 70 psi oil pressure unlikely. The only rod bearings I have heard of spinning was from a loss of oil pressure, and galling the bearing surface to the point that it tries to weld itself to the crank, spinning inside the rod. If it is continually run, the outside of the bearing will gall, and try to weld itself to the rod, at which point, the rod goes through the side of the block.
As far as your original question, I don't think you have anything to worry about. The FSM gives a minimum of 4.3 psi at idle (no maximum) and 36 - 71 psi at 3000 rpm. That should be the relief point for the bypass valve. As the oil pump wears, and the bearings wear, it will reduce this pressure. Also, all of the oil that is used in the bearings is first forced through the filter, reducing the final supply pressure. The 22r reads the pressure before the filter. So, if your filter is totally clogged, you may have a good pressure reading, but be supplying no oil to your engine (unless the filter has a by-pass valve in it).
