Olblu I am running a rebuilt 235 with about 30k miles on it. my oil pressure has always stayed at 20 lbs at idle and 45 lbs going down the road at 60 to 70 mph with the engine at operating temperatures. Are you sure you don't have a babbited engine? A change to 30 wt oil will bring the pressure up some but something is not right with nearly zero oil pressure at idle. The clattering lifters are telling you the pressure is not high enough. Install another pressure gauge to eleminate the problem with the gauge. I would check out bearing clearance before something is ruined. A bad oil pump is a possibility. The mains and insert bearings may be too loose?
