I would use ARP rod bolts, the main caps bolts can be left as they are std ford.
With the oil pressure you have this certainly doesn't sound like a worn crank/shells, they are the same on escos as sierra, the thrusts only control end float so won't make a noise if shagged, and would be the last ones to go as well.
Very hard to say what it is without hearing but most likely lazy tappets, or piston slap if on 2wd pistons are someone cocked up on the bore clearances, I run 1 1/2 thou, a lot run more.
tabetha