'89 roller-cam LA 360 w/Magnum heads - new roller lifters not pumping up

Is there a plug behind the chain tension plate,
for the driver's side lifter galley

Yes, both plugs are there.

Left plug has a small hole (bit smaller than the lifter itself) drilled in it from factory so that it oils the timing chain, discussed in detail here: http://www.forabodiesonly.com/mopar/showthread.php?t=323094. Hole is not enough to cause a major loss in pressure.

The bigger hole that you see in the new cam thrust plate replicates the same hole that the factory one had:



Just another one of Mopar's countless experiments trying to improve (or cost cut) their timing chain oiling system. Does roughly the same thing as the drilled bolt without having to stock a drilled bolt at the factory.

-Kurt