[MagicRat]

I think you have 2 problems.
First of all, 70-75 psi of pressure is a little high, assuming your gauge is accurate. The oil pressure relief valve may be stuck closed.
Usually, the valve opens to bleed-off excess pressure, so it is limited to 35-45 psi, regardless of engine revs. . Also, pressure 'flutter' (at pressures that high) is usually never observed, again because excess pressure is bled off, which serves to moderate such fluctuations.

High oil pressure puts excess stress on the oil pump drive mechanism and may cause your oil filter to rupture.

As for the gas in the oil... people have used gas, diesel, kerosene etc to clean-up sludge deposits inside an engine, so I wonder if a bit of sludge has broken free, got sucked up by the oil pump and has jammed the pressure relief valve??

Also, gas in oil obviously thins the oil and can easily cause metal-to-metal contact in the crankshaft bearings, causing damage.

At the very least, consider dropping the oil pan and removing all bearing caps. Inspect the bearings for wear, damage etc. If the damage is moderate, the crankshaft could be machined and all-new, undersized bearings installed. If you are lucky, the engine does not need to be removed to do this job.

It sounds like the damage is not too severe right now. Badly-damaged bearings tend to "spin", that is, the bearing shells are overheated so much they weld themselves to the crankshaft journal and start to spin in the bearing saddles. This means the bearing saddles and caps need to be re-sized before installation... which is a major machine-shop job and requires engine removal from the vehicle.

Finally, replace the oil pump too.