Intermittent oil pressure/lack of oil pressure

5-30 is alfulll thin for a old mopar. If its a new rebuild with real tight clearances maybe but stock original I would go with one of the 15-40 diesel oils. That said have had a oil filter collapse inside and cause a basicaly 0 oil pressure. My guess is your filter was to blame. I guess that there is a chance that any brand filter can fail but you can better your odds by sticking with a quality brand like Wix or peroilater.