Yep, either oil pump or the oil pan is smashed. The older DE's have a crappy pickup tube that can be easily completely blocked if smashed up against the pan. The pickup tube went through a revision later where it has two upward notches just incase that happens but still could and will starve the engine of oil if its smashed enough.
Need to find the cause of the problem first.
Really worn bearings can also cause low oil pressure at idle but you would really hear it knocking loud if that were the case.
As for the bearings, If you want a stronger harder bearing than stocks ACL Race bearings (non coated) are the way to go. OEM's are good but they are also soft.
Cant beat the price of the ACL's. Get them in standard size. Either way I suggest pulling the pans, Prior to doing that look at the pan and if the center of the pan is in any way shape or form dented or not sitting even or lower than the edges of the pan, then more than likely its up against the pickup tube. Under normal conditions the pickup tube only sits less than a 1/4" away from the bottom of the pan. If the pan checks out good, check your oil pickup tube for any cracking. If thats good I would replace the oil pump with a new unit and also do the bearings while your at it. Get a new gasket for the pickup tube and make sure to hammer down the pan if its dented at all.