Vz low oil pressure at revs and under load

[MT92]

Hi, I have a 2005 vz Storm ute. I recently had the notorious timing chains issue. I had the chains, tensioners, guides and idler gears replaced. Since that job was done I now have an issue with top end noise that only happens when I am driving the car and I hit 2000 to 2500 revs. It doesn't do it in neutral or park only under load once I hit those revs. I have opened the top end up and also removed the sump to do the oil pick up and clean up any gunk or sludge in the motor but I am still getting the issues. I've also tried running detergent oil through and different viscosities etc etc and nothing. Any ideas on what this could be??